cancer

(redirected from AIDS-related cancer)
Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

Cancer

 

Definition

Cancer is not just one disease, but a large group of almost 100 diseases. Its two main characteristics are uncontrolled growth of the cells in the human body and the ability of these cells to migrate from the original site and spread to distant sites. If the spread is not controlled, cancer can result in death.

Description

One out of every four deaths in the United States is from cancer. It is second only to heart disease as a cause of death in the states. About 1.2 million Americans are diagnosed with cancer annually; more than 500,000 die of cancer annually.
Cancer can attack anyone. Since the occurrence of cancer increases as individuals age, most of the cases are seen in adults, middle-aged or older. Sixty percent of all cancers are diagnosed in people who are older than 65 years of age. The most common cancers are skin cancer, lung cancer, colon cancer, breast cancer (in women), and prostate cancer (in men). In addition, cancer of the kidneys, ovaries, uterus, pancreas, bladder, rectum, and blood and lymph node cancer (leukemias and lymphomas) are also included among the 12 major cancers that affect most Americans.
Cancer, by definition, is a disease of the genes. A gene is a small part of DNA, which is the master molecule of the cell. Genes make "proteins," which are the ultimate workhorses of the cells. It is these proteins that allow our bodies to carry out all the many processes that permit us to breathe, think, move, etc.
Throughout people's lives, the cells in their bodies are growing, dividing, and replacing themselves. Many genes produce proteins that are involved in controlling the processes of cell growth and division. An alteration (mutation) to the DNA molecule can disrupt the genes and produce faulty proteins. This causes the cell to become abnormal and lose its restraints on growth. The abnormal cell begins to divide uncontrollably and eventually forms a new growth known as a "tumor" or neoplasm (medical term for cancer meaning "new growth").
In a healthy individual, the immune system can recognize the neoplastic cells and destroy them before they get a chance to divide. However, some mutant cells may escape immune detection and survive to become tumors or cancers.
Tumors are of two types, benign or malignant. A benign tumor is not considered cancer. It is slow growing, does not spread or invade surrounding tissue, and once it is removed, doesn't usually recur. A malignant tumor, on the other hand, is cancer. It invades surrounding tissue and spreads to other parts of the body. If the cancer cells have spread to the surrounding tissues, even after the malignant tumor is removed, it generally recurs.
A majority of cancers are caused by changes in the cell's DNA because of damage due to the environment. Environmental factors that are responsible for causing the initial mutation in the DNA are called carcinogens, and there are many types.
There are some cancers that have a genetic basis. In other words, an individual could inherit faulty DNA from his parents, which could predispose him to getting cancer. While there is scientific evidence that both factors (environmental and genetic) play a role, less than 10% of all cancers are purely hereditary. Cancers that are known to have a hereditary link are breast cancer, colon cancer, ovarian cancer, and uterine cancer. Besides genes, certain physiological traits could be inherited and could contribute to cancers. For example, inheriting fair skin makes a person more likely to develop skin cancer, but only if he or she also has prolonged exposure to intensive sunlight.
There are several different types of cancers:
  • Carcinomas are cancers that arise in the epithelium (the layer of cells covering the body's surface and lining the internal organs and various glands). Ninety percent of human cancers fall into this category. Carcinomas can be subdivided into two types: adenocarcinomas and squamous cell carcinomas. Adenocarcinomas are cancers that develop in an organ or a gland, while squamous cell carcinomas refer to cancers that originate in the skin.
  • Melanomas also originate in the skin, usually in the pigment cells (melanocytes).
  • Sarcomas are cancers of the supporting tissues of the body, such as bone, muscle and blood vessels.
  • Cancers of the blood and lymph glands are called leukemias and lymphomas respectively.
  • Gliomas are cancers of the nerve tissue.

Causes and symptoms

The major risk factors for cancer are: tobacco, alcohol, diet, sexual and reproductive behavior, infectious agents, family history, occupation, environment and pollution.
According to estimates of the American Cancer Society (ACS), approximately 40% of cancer deaths in 1998 were due to tobacco and excessive alcohol use. An additional one-third of the deaths were related to diet and nutrition. Many of the one million skin cancers diagnosed in 1998 were due to over-exposure to ultraviolet light from the sun's rays.
Frequency Of Cancer-Related Death
Cancer Site Number of Deaths Per Year
Lung 160,100
Colon and rectum 56,500
Breast 43,900
Prostate 39,200
Pancreas 28,900
Lymphoma 26,300
Leukemia 21,600
Brain 17,400
Stomach 13,700
Liver 13,000
Esophagus 11,900
Bladder 12,500
Kidney 11,600
Multiple myeloma 11,300

Tobacco

Eighty to 90% of lung cancer cases occur in smokers. Smoking has also been shown to be a contributory factor in cancers of upper respiratory tract, esophagus, larynx, bladder, pancreas, and probably liver, stomach, breast, and kidney as well. Recently, scientists have also shown that second-hand smoke (or passive smoking) can increase one's risk of developing cancer.

Alcohol

Excessive consumption of alcohol is a risk factor in certain cancers, such as liver cancer. Alcohol, in combination with tobacco, significantly increases the chances that an individual will develop mouth, pharynx, larynx, and esophageal cancers.

Diet

Thirty-five percent of all cancers are due to dietary causes. Excessive intake of fat leading to obesity has been associated with cancers of the breast, colon, rectum, pancreas, prostate, gall bladder, ovaries, and uterus.

Sexual and reproductive behavior

The human papillomavirus, which is sexually transmitted, has been shown to cause cancer of the cervix. Having too many sex partners and becoming sexually active early has been shown to increase one's chances of contracting this disease. In addition, it has also been shown that women who don't have children or have children late in life have an increased risk for both ovarian and breast cancer.

Infectious agents

In the last 20 years, scientists have obtained evidence to show that approximately 15% of the world's cancer deaths can be traced to viruses, bacteria, or parasites. The most common cancer-causing pathogens and the cancers associated with them are shown in table form.

Family history

Certain cancers like breast, colon, ovarian, and uterine cancer recur generation after generation in some families. A few cancers, such as the eye cancer "retinoblastoma," a type of colon cancer, and a type of breast cancer known as "early-onset breast cancer," have been shown to be linked to certain genes that can be tracked within a family. It is therefore possible that inheriting particular genes makes a person susceptible to certain cancers.

Occupational hazards

There is evidence to prove that certain occupational hazards account for 4% of all cancer deaths. For example, asbestos workers have an increased incidence of lung cancer. Similarly, a higher likelihood of getting bladder cancer is associated with dye, rubber and gas workers; skin and lung cancer with smelters, gold miners and arsenic workers; leukemia with glue and varnish workers; liver cancer with PVC manufacturers; and lung, bone and bone marrow cancer with radiologists and uranium miners.

Environment

Radiation is believed to cause 1-2% of all cancer deaths. Ultra-violet radiation from the sun accounts for a majority of melanoma deaths. Other sources of radiation are x rays, radon gas, and ionizing radiation from nuclear material.

Pollution

Several studies have shown that there is a well-established link between asbestos and cancer. Chlorination of water may account for a small rise in cancer risk. However, the main danger from pollution occurs when dangerous chemicals from the industries escape into the surrounding environment. It has been estimated that 1% of cancer deaths are due to air, land, and water pollution.
COMMON PATHOGENS AND THE CANCERS ASSOCIATED WITH THEM
Causative Agent Type of Cancer
Viruses
Papillomaviruses Cancer of the cervix
Hepatitis B virus Liver cancer
Hepatitis C virus Liver cancer
Epstein-Barr virus Burkitt's lymphoma
Cancers of the upper
pharynx
Hodgkin's lymphoma, Non-Hodgkin's
lymphoma, Gastric cancers
Human
immunodeficiency
virus (HIV)
Kaposi's sarcoma Lymphoma
Bacteria
Helicobacter pylori Stomach cancer Lymphomas
Cancer is a progressive disease, and goes through several stages. Each stage may produce a number of symptoms. Some symptoms are produced early and may occur due to a tumor that is growing within an organ or a gland. As the tumor grows, it may press on the nearby nerves, organs, and blood vessels. This causes pain and some pressure which may be the earliest warning signs of cancer.
Despite the fact that there are several hundred different types of cancers, producing very different symptoms, the ACS has established the following seven symptoms as possible warning signals of cancer:
  • changes in the size, color, or shape of a wart or a mole
  • a sore that does not heal
  • persistent cough, hoarseness, or sore throat
  • a lump or thickening in the breast or elsewhere
  • unusual bleeding or discharge
  • chronic indigestion or difficulty in swallowing
  • any change in bowel or bladder habits
Many other diseases, besides cancer, could produce the same symptoms. However, it is important to have these symptoms checked, as soon as possible, especially if they linger. The earlier a cancer is diagnosed and treated, the better the chance of it being cured. Many cancers such as breast cancer may not have any early symptoms. Therefore, it is important to undergo routine screening tests such as breast self-exams and mammograms.

Diagnosis

Diagnosis begins with a thorough physical examination and a complete medical history. The doctor will observe, feel and palpate (apply pressure by touch) different parts of the body in order to identify any variations from the normal size, feel, and texture of the organ or tissue.
As part of the physical exam, the doctor will inspect the oral cavity, or the mouth. By focusing a light into the mouth, he will look for abnormalities in color, moisture, surface texture, or presence of any thickening or sore in the lips, tongue, gums, the hard palate on the roof of the mouth, and the throat. To detect thyroid cancer, the doctor will observe the front of the neck for swelling. He may gently manipulate the neck and palpate the front and side surfaces of the thyroid gland (located at the base of the neck) to detect any nodules or tenderness. As part of the physical examination, the doctor will also palpate the lymph nodes in the neck, under the arms and in the groin. Many illnesses and cancers cause a swelling of the lymph nodes.
The doctor may conduct a thorough examination of the skin to look for sores that have been present for more than three weeks and that bleed, ooze, or crust; irritated patches that may itch or hurt, and any change in the size of a wart or a mole.
Examination of the female pelvis is used to detect cancers of the ovaries, uterus, cervix, and vagina. In the visual examination, the doctor looks for abnormal discharges or the presence of sores. Then, using gloved hands the physician palpates the internal pelvic organs such as the uterus and ovaries to detect any abnormal masses. Breast examination includes visual observation where the doctor looks for any discharge, unevenness, discoloration, or scaling. The doctor palpates both breasts to feel for masses or lumps.
For males, inspection of the rectum and the prostate is also included in the physical examination. The doctor inserts a gloved finger into the rectum and rotates it slowly to feel for any growths, tumors, or other abnormalities. The doctor also conducts an examination of the testes, where the doctor observes the genital area and looks for swelling or other abnormalities. The testicles are palpated to identify any lumps, thickening or differences in the size, weight and firmness.
If the doctor detects an abnormality on physical examination, or the patient has some symptom that could be indicative of cancer, the doctor may order diagnostic tests.
Laboratory studies of sputum (sputum cytology), blood, urine, and stool can detect abnormalities that may indicate cancer. Sputum cytology is a test where the phlegm that is coughed up from the lungs is microscopically examined. It is often used to detect lung cancer. A blood test for cancer is easy to perform, usually inexpensive and risk-free. The blood sample is obtained by a lab technician or a doctor by inserting a needle into a vein and is relatively painless. Blood tests can be either specific or non-specific. Often, in certain cancers, the cancer cells release particular proteins (called tumor markers) and blood tests can be used to detect the presence of these tumor markers. However, with a few exceptions, tumor markers are not used for routine screening of cancers, because several non-cancerous conditions also produce positive results. Blood tests are generally more useful in monitoring the effectiveness of the treatment, or in following the course of the disease and detecting recurrent disease.
Imaging tests such as computed tomography scans (CT scans), magnetic resonance imaging (MRI), ultrasound and fiberoptic scope examinations help the doctors determine the location of the tumor even if it is deep within the body. Conventional x rays are often used for initial evaluation, because they are relatively cheap, painless and easily accessible. In order to increase the information obtained from a conventional x ray, air or a dye (such as barium or iodine) may be used as a contrast medium to outline or highlight parts of the body.
The most definitive diagnostic test is the biopsy, wherein a piece of tissue is surgically removed for microscope examination. Besides confirming a cancer, the biopsy also provides information about the type of cancer, the stage it has reached, the aggressiveness of the cancer and the extent of its spread. Since a biopsy provides the most accurate analysis, it is considered the gold standard of diagnostic tests.
Screening examinations conducted regularly by healthcare professionals can result in the detection of cancers of the breast, colon, rectum, cervix, prostate, testis, tongue, mouth, and skin at early stages, when treatment is more likely to be successful. Some of the routine screening tests recommended by the ACS are sigmoidoscopy (for colorectal cancer), mammography (for breast cancer), pap smear (for cervical cancer), and the PSA test (for prostate cancer). Self-examinations for cancers of the breast, testes, mouth, and skin can also help in detecting the tumors before the symptoms become serious.
A recent revolution in molecular biology and cancer genetics has contributed a great deal to the development of several tests designed to assess one's risk of getting cancers. These new techniques include genetic testing, where molecular probes are used to identify mutations in certain genes that have been linked to particular cancers. At present, however, there are a lot of limitations to genetic testing and its utility appears ambiguous, emphasizing the need to develop better strategies for early detection.

Treatment

Treatment and prevention of cancers continue to be the focus of a great deal of research. In 2003, research into new cancer therapies included cancertargeting gene therapy, virus therapy, and a drug that stimulated apoptosis, or self-destruction of cancer cells, but not healthy cells. However, all of these new therapies take years of clinical testing and research.
The aim of cancer treatment is to remove all or as much of the tumor as possible and to prevent the recurrence or spread of the primary tumor. While devising a treatment plan for cancer, the likelihood of curing the cancer has to be weighed against the side effects of the treatment. If the cancer is very aggressive and a cure is not possible, then the treatment should be aimed at relieving the symptoms and controlling the cancer for as long as possible.
Cancer treatment can take many different forms, and it is always tailored to the individual patient. The decision on which type of treatment is the most appropriate depends on the type and location of cancer, the extent to which it has already spread, the patient's age, sex, general health status and personal treatment preferences. The major types of treatment are: surgery, radiation, chemotherapy, immunotherapy, hormone therapy, and bone-marrow transplantation.

Surgery

Surgery is the removal of a visible tumor and is the most frequently used cancer treatment. It is most effective when a cancer is small and confined to one area of the body.
Surgery can be used for many purposes.
  • Treatment. Treatment of cancer by surgery involves removal of the tumor to cure the disease. This is typically done when the cancer is localized to a discrete area. Along with the cancer, some part of the normal surrounding tissue is also removed to ensure that no cancer cells remain in the area. Since cancer usually spreads via the lymphatic system, adjoining lymph nodes may be examined and sometimes are removed as well.
  • Preventive surgery. Preventive or prophylactic surgery involves removal of an abnormal looking area that is likely to become malignant over time. For example, 40% of people with a colon disease known as ulcerative colitis, ultimately die of colon cancer. Rather than live with the fear of developing colon cancer, these people may choose to have their colons removed and reduce the risk significantly.
  • Diagnostic purposes. The most definitive tool for diagnosing cancer is a biopsy. Sometimes, a biopsy can be performed by inserting a needle through the skin. However, at other times, the only way to obtain a tissue sample for biopsy is by performing a surgical operation.
  • Cytoreductive surgery is a procedure where the doctor removes as much of the cancer as possible, and then treats the remaining area with radiation therapy or chemotherapy or both.
  • Palliative surgery is aimed at curing the symptoms, not the cancer. Usually, in such cases, the tumor is so large or has spread so much that removing the entire tumor is not an option. For example, a tumor in the abdomen may be so large that it may press on and block a portion of the intestine, interfering with digestion and causing pain and vomiting. "Debulking surgery" may remove a part of the blockage and relieve the symptoms. In tumors that are dependent on hormones, removal of the organs that secrete the hormones is an option. For example, in prostate cancer, the release of testosterone by the testicles stimulates the growth of cancerous cells. Hence, a man may undergo an "orchiectomy" (removal of testicles) to slow the progress of the disease. Similarly, in a type of aggressive breast cancer, removal of the ovaries (oophorectomy) will stop the synthesis of hormones from the ovaries and slow the progression of the cancer.

Radiation therapy

Radiation kills tumor cells. Radiation is used alone in cases where a tumor is unsuitable for surgery. More often, it is used in conjunction with surgery and chemotherapy. Radiation can be either external or internal. In the external form, the radiation is aimed at the tumor from outside the body. In internal radiation (also known as brachytherapy), a radioactive substance in the form of pellets or liquid is placed at the cancerous site by means of a pill, injection or insertion in a sealed container.

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. It destroys the hard-to-detect cancer cells that have spread and are circulating in the body. Chemotherapeutic drugs can be taken either orally (by mouth) or intravenously, and may be given alone or in conjunction with surgery, radiation or both.
When chemotherapy is used before surgery or radiation, it is known as primary chemotherapy or "neoadjuvant chemotherapy." An advantage of neoadjuvant chemotherapy is that since the cancer cells have not been exposed to anti-cancer drugs, they are especially vulnerable. It can therefore be used effectively to reduce the size of the tumor for surgery or target it for radiation. However, the toxic effects of neoadjuvant chemotherapy are severe. In addition, it may make the body less tolerant to the side effects of other treatments that follow such as radiation therapy. The more common use of chemotherapy is adjuvant therapy, which is given to enhance the effectiveness of other treatments. For example, after surgery, adjuvant chemotherapy is given to destroy any cancerous cells that still remain in the body. In 2003, a new technique was developed to streamline identification of drug compounds that are toxic to cancerous cells but not to healthy cells. The technique identified nine dugs, one of which had never before been identified for use in cancer treatment. Researchers began looking into developing the new drug for possible use.

Immunotherapy

Immunotherapy uses the body's own immune system to destroy cancer cells. This form of treatment is being intensively studied in clinical trials and is not yet widely available to most cancer patients. The various immunological agents being tested include substances produced by the body (such as the interferons, interleukins, and growth factors), monoclonal antibodies, and vaccines. Unlike traditional vaccines, cancer vaccines do not prevent cancer. Instead, they are designed to treat people who already have the disease. Cancer vaccines work by boosting the body's immune system and training the immune cells to specifically destroy cancer cells.

Hormone therapy

Hormone therapy is standard treatment for some types of cancers that are hormone-dependent and grow faster in the presence of particular hormones. These include cancer of the prostate, breast, and uterus. Hormone therapy involves blocking the production or action of these hormones. As a result the growth of the tumor slows down and survival may be extended for several months or years.

Bone marrow transplantation

The bone marrow is the tissue within the bone cavities that contains blood-forming cells. Healthy bone marrow tissue constantly replenishes the blood supply and is essential to life. Sometimes, the amount of drugs or radiation needed to destroy cancer cells also destroys bone marrow. Replacing the bone marrow with healthy cells counteracts this adverse effect. A bone marrow transplant is the removal of marrow from one person and the transplant of the blood-forming cells either to the same person or to someone else. Bone-marrow transplantation, while not a therapy in itself, is often used to "rescue" patients, by allowing those with cancer to undergo aggressive therapy.
Many different specialists generally work together as a team to treat cancer patients. An oncologist is a physician who specializes in cancer care. The oncologist provides chemotherapy, hormone therapy, and any other non-surgical treatment that does not involve radiation. The oncologist often serves as the primary physician and coordinates the patient's treatment plan.
The radiation oncologist specializes in using radiation to treat cancer, while the surgical oncologist performs the operations needed to diagnose or treat cancer. Gynecologist-oncologists and pediatric-oncologists, as their titles suggest, are physicians involved with treating women's and children's cancers respectively. Many other specialists also may be involved in the care of a cancer patient. For example, radiologists specialize in the use of x rays, ultrasounds, CT scans, MRI imaging and other techniques that are used to diagnose cancer. Hematologists specialize in disorders of the blood and are consulted in case of blood cancers and bone marrow cancers. The samples that are removed for biopsy are sent to a laboratory, where a pathologist examines them to determine the type of cancer and extent of the disease. Only some of the specialists who are involved with cancer care have been mentioned above. There are many other specialties, and virtually any type of medical or surgical specialist may become involved with care of the cancer patient should it become necessary.

Alternative treatment

There are a multitude of alternative treatments available to help the person with cancer. They can be used in conjunction with, or separate from, surgery, chemotherapy, and radiation therapy. Alternative treatment of cancer is a complicated arena and a trained health practitioner should be consulted.
Although the effectiveness of complementary therapies such as acupuncture in alleviating cancer pain has not been clinically proven, many cancer patients find it safe and beneficial. Bodywork therapies such as massage and reflexology ease muscle tension and may alleviate side effects such as nausea and vomiting. Homeopathy and herbal remedies used in Chinese traditional herbal medicine also have been shown to alleviate some of the side effects of radiation and chemotherapy and are being recommended by many doctors.
Certain foods including many vegetables, fruits, and grains are believed to offer protection against various cancers. However, isolation of the individual constituent of vegetables and fruits that are anti-cancer agents has proven difficult. In laboratory studies, vitamins such as A, C and E, as well as compounds such as isothiocyanates and dithiolthiones found in broccoli, cauliflower, and cabbage, and beta-carotene found in carrots have been shown to protect against cancer. Studies have shown that eating a diet rich in fiber as found in fruits and vegetables reduces the risk of colon cancer. Exercise and a low fat diet help control weight and reduce the risk of endometrial, breast, and colon cancer.
Certain drugs, which are currently being used for treatment, could also be suitable for prevention. For example, the drug tamoxifen (Nolvadex), which has been very effective against breast cancer, is currently being tested by the National Cancer Institute for its ability to prevent cancer. Similarly, retinoids derived from vitamin A are being tested for their ability to slow the progression or prevent head and neck cancers. Certain studies have suggested that cancer incidence is lower in areas where soil and foods are rich in the mineral selenium. More trials are needed to explain these intriguing connections.

Prognosis

"Lifetime risk" is the term that cancer researchers use to refer to the probability that an individual over the course of a lifetime will develop cancer or die from it. In the United States, men have a one in two lifetime risk of developing cancer, and for women the risk is one in three. Overall, African Americans are more likely to develop cancer than whites. African Americans are also 30% more likely to die of cancer than whites.
Most cancers are curable if detected and treated at their early stages. A cancer patient's prognosis is affected by many factors, particularly the type of cancer the patient has, the stage of the cancer, the extent to which it has metastasized and the aggressiveness of the cancer. In addition, the patient's age, general health status and the effectiveness of the treatment being pursued also are important factors.
To help predict the future course and outcome of the disease and the likelihood of recovery from the disease, doctors often use statistics. The five-year survival rates are the most common measures used. The number refers to the proportion of people with cancer who are expected to be alive, five years after initial diagnosis, compared with a similar population that is free of cancer. It is important to note that while statistics can give some information about the average survival experience of cancer patients in a given population, it cannot be used to indicate individual prognosis, because no two patients are exactly alike.

Prevention

According to nutritionists and epidemiologists from leading universities in the United States, a person can reduce the chances of getting cancer by following some simple guidelines:
  • eating plenty of vegetables and fruits
  • exercising vigorously for at least 20 minutes every day
  • avoiding excessive weight gain
  • avoiding tobacco (even second hand smoke)
  • decreasing or avoiding consumption of animal fats and red meats
  • avoiding excessive amounts of alcohol
  • avoiding the midday sun (between 11 A.M. and 3 P.M.) when the sun's rays are the strongest
  • avoiding risky sexual practices
  • avoiding known carcinogens in the environment or work place
In addition, following the advice of physicians in refraining from certain activities or drugs that are proven as risk factors for certain cancers can help lower one's risk. For instance, while physicians have long known a small increased risk for breast cancer was linked to use of HRT, a landmark study released in 2003 proved the risk was greater than thought. The Women's Health Initiative found that even relatively short-term use of estrogen plus progestin is associated with increased risk of breast cancer, diagnosis at a more advanced stage of the disease, and a higher number of abnormal mammograms. The longer a woman used HRT, the more her risk increased.

Resources

Books

Simone, Joseph V. "Oncology: Introduction." In Cecil Textbook of Medicine, edited by Russel L. Cecil, et al. Philadelphia: W.B. Saunders Company, 2000.

Periodicals

"HRT Linked to Higher Breast Cancer Risk, Later Diagnosis, Abnormal Mammograms." Women's Health Weekly July 17, 2003: 2.
"New Way to Stop Cancer Cell Growth Described." Gene Therapy Weekly December 12, 2002: 9.
"Researchers Find New Way to Trigger Self-Destruction of Certain Cancer Cells." Biotech Week July 16, 2003: 285.
"Technique Streamlines Search for Anticancer Drugs." Cancer Weekly April 15, 2003: 62.
"Virus Therapy Attacks Cancer Cells." Cancer Weekly July 29, 2003: 50.

Organizations

American Cancer Society. 1599 Clifton Road, N.E. Atlanta, GA 30329 (800) 227-2345. http://www.cancer.org.
Cancer Research Institute (National Headquarters). 681, Fifth Avenue, New York, NY 10022 (800) 992-2623. http://www.cancerresearch.org.
National Cancer Institute. 9000 Rockville Pike, Building 31, room 10A16, Bethesda, Maryland, 20892 (800) 422-6237. http://wwwicic.nci.nih.gov.

cancer

 [kan´ser]
any malignant, cellular tumor. For specific types, see under the name, such as breast cancer or lung cancer. adj., adj can´cerous.

The term cancer encompasses a group of neoplastic diseases in which there is a transformation of normal body cells into malignant ones. This probably involves some change in the genetic material of the cells, deoxyribonucleic acid (DNA). oncogenes are the genes that organisms have evolved to regulate growth and repair of tissues. They are genetic codes for the proteins that function as signals that cells send and receive to regulate proliferation. These oncogenes are the targets of carcinogens. mutation and transformation of oncogenes may permanently affect a cell's ability to control cell growth. Damage to the cell's genetic material may be caused by carcinogenic agents. Normal cell lines can be transformed into cancer cells by viruses, chemical carcinogens, and radiation. Transformed cell lines have the ability to develop into malignant neoplasms. Transformed cells may also be recognized by other characteristics which include altered antigenicity, diminished contact inhibition, reduced requirements for certain nutrients, and the ability to grow in suspension. The altered cells pass on inappropriate genetic information to their offspring and begin to proliferate in an abnormal and destructive way. Normally, cells reproduce regularly to replace worn-out tissues, repair injuries, and allow for growth during the developing years. After these processes have taken place, cellular reproduction stops. Clearly the body in its normal processes regulates cell growth in an orderly manner. In cancer, there is no regulation and cell reproduction and growth is disorderly. The dangers of cancer are related to this chaotic reproduction of malignant cells.

As the cancer cells continue to proliferate, the mass of abnormal tissue that they form enlarges, ulcerates, and begins to shed cells that spread the disease locally or to distant sites. This migration is called metastasis. Some cells penetrate neighboring tissues, destroying normal cells and taking their place. Others can enter the blood stream and lymphatic vessels and be carried along in the fluid to another part of the body. Another way malignancy can be spread is by entering a body cavity and coming in contact with a healthy organ; however, this is not common.
Causes. It is doubtful that one process is involved in the etiology of all cancers. The exact cause of conversion of normal cells into cancerous ones is still not completely understood. An important factor is permanent alteration in the DNA of the cell, which is passed on to subsequent generations, but we do not know what triggers the change in DNA structure and why some people succumb to a cancer and others do not. Cellular immunity undoubtedly plays some part in one's ability to stop the growth of cancer cells; it is believed by some that most persons develop many small cancers in their lifetime but do not develop clinical signs because their defense mechanisms destroy the malignant cells and prevent their replication.

Oncologists recognize that environmental, hereditary, and biological factors all play important roles in the development of cancer (see table). Environmental causes are believed to account for at least 50 per cent and perhaps, in some types, as much as 80 per cent of all cancers. For example, cigarette smoking is directly related to approximately 90 per cent of all cases of lung cancer. Other environmental carcinogens include industrial pollutants and radiation. Among the chemical carcinogens are arsenic from mining and smelting industries; asbestos from insulation, at construction sites and power plants; benzene from oil refineries, solvents, and insecticides; and products from coal combustion in steel and petrochemical industries. Each year new products that in all probability are carcinogenic are being produced by industrial operations. A major concern is the occupational and environmental hazards these chemicals present to those who work in or live near these plants.

Radiation from prolonged exposure to the ultraviolet rays of the sun or from injudicious use of diagnostic and therapeutic procedures involving x-rays and radioactive substances is also a significant factor in the incidence of cancer, particularly that of the skin, bone marrow, and thyroid.

Hormones, especially the synthetic estrogens given to prevent spontaneous abortion, are directly related to some cancers of the female reproductive organs.

Viruses as causal agents in the development of cancer have been subjected to intensive research efforts in recent years. The epidemiologic evidence is strongest for a relationship between hepatitis B virus and hepatocellular carcinoma and between human T-lymphotropic virus (HTLV)-1 and T-cell lymphoma. Both have a geographic distribution of cancer prevalence and viral infection as well as case-by-case associations. The association between burkitt's lymphoma and epstein-barr virus (EBV) is likewise strong, except that there seems to be a need for an associated immunodeficiency state, such as that induced by chronic malaria. Similarly, the association between EBV and high-grade lymphoma in Western countries seems to require that an immunodeficiency state be present, either congenital or induced by the human immunodeficiency virus (HIV) or a drug such as cyclosporine.

The intriguing fact has been noted that viruses are capable of introducing new genetic material into a normal cell and transforming it into a malignant one, and that cell reproduction may be altered when viruses interact with such carcinogens as chemicals and radiation. Recent studies have shown that an extracellular enzyme, reverse transcriptase, plays an important role in the transmission of genetic information to the cell and thereby facilitates the reproduction of cancer cells.

The incidence of cancer in certain populations suggests that other factors are important in its development. It is known, for example, that some families show a high incidence of malignancy among their members, but there is no definite hereditary pattern. There also is a high incidence of cancer in persons receiving drugs for immunosuppression, yet cancer itself is immunosuppressive. It is suggested that prolonged suppression of the body's immune response may eventually impair its ability to distinguish between self and nonself and thus render it unable to destroy malignant cells. When cancer itself acts to suppress the immune response, it may be the result of an overwhelming demand on the body to destroy more foreign cells than it is prepared to cope with at any given time.

Aging is another factor to consider in development of malignancy. Although cancer can occur at any age, older persons are more susceptible, perhaps because their powers of adaptability are weakened and they have been exposed to carcinogens longer than have younger persons.
Classification. Cancers are classified on the basis of two factors: the type of tissue and the type of cell in which they arise. Using this classification system, it is possible to identify over 150 types of cancer in humans. In the classification of cancers according to the type of tissue from which they evolve, there are two main groups, sarcomas and carcinomas. Sarcomas are of mesenchymal origin and affect such tissues as the bones and muscles; they tend to grow rapidly and to be very destructive. The carcinomas are of epithelial origin and make up the great majority of the glandular cancers and cancers of the breast, stomach, uterus, skin, and tongue. Cell type affects the appearance, rate of growth, and degree of malignancy. Thus, classification of tumors according to the type of cell from which they are derived is important in deciding the course of treatment for a specific malignancy.

Staging. An approach to describing and categorizing malignant tumors has been developed by the International Union Against Cancer (UICC) and the American Joint Committee on Cancer (AJCC). It is hoped that by standardizing the classification and staging of tumors, treatment protocols can be established and end results reporting can be utilized to determine the effectiveness of the suggested treatment. Whereas classification of tumors refers to the anatomical and histological descriptions of the tumor (see above), staging refers to the extent of the tumor. The three components of the staging system are the primary tumor (T), regional nodes (N), and metastasis (M). Subscripts may be used to describe the extent to which the malignancy has increased in size, its involvement of regional nodes, and its metastatic development (see table). For example, a tumor may be described as T1N2M0. dukes' classification is a system of staging colorectal tumors, based on the depth of invasion and degree of metastasis.

Precancers. Some potentially dangerous cancers appear first in the form of harmless changes in the body's tissues. The danger lies in the fact that such changes have a tendency to become malignant; hence they are known as precancers. Among them are sores that appear as thickened white patches (leukoplakia) in the mouth and on the vulva, some moles, and any chronically irritated area on the skin or the mucous membranes of the mouth and tongue. polyps are also possible precancers.
Prevention. Because environmental conditions play an important role in the etiology of many cancers, prevention is aimed at identifying carcinogens, educating the general public about them, and encouraging their avoidance. Equally important, if not more so, is recognition of causative factors related to life style and personal habits. Perhaps the best example of this is the relationship between smoking and lung cancer. When heavy consumption of alcohol is combined with cigarette smoking, the risk for cancer of the larynx, esophagus, and mouth is greatly increased.

Nutritional balance is also important in the prevention of cancer. Certain foods and food additives contain specific carcinogenic agents. Nutritional deficiency can lower resistance and increase the risk of certain types of cancers. The decrease in incidence of stomach cancer in most Western countries may possibly be the result of an increase in consumption of fruits and vegetables, since vitamin B12 deficiency (pernicious anemia) is known to be related to increased incidence of stomach cancer.

Studies have shown that a relationship exists between obesity and cancer, and between dietary excess, particularly consumption of large amounts of fats, and certain types of cancers. In general, overweight women are at increased risk for cancer of the endometrium, gallbladder, and kidney. Cancers associated with a high dietary intake of fat, with or without obesity, are those affecting the breast, ovary, endometrium, prostate, colon, and pancreas. Although neither saturated nor unsaturated fats are themselves carcinogenic, they act on the endocrine system and affect hormonal activity. The relationship of fat consumption to colon cancer is thought to be due to the effect of bile acids and their metabolites, which have been shown to act as tumor promoters in laboratory animals. In humans, patients with cancer of the colon typically have elevated levels of bile acid metabolites. Studies of various populations throughout the world have shown that bowel cancer is more prevalent among groups who eat large amounts of fat and very little food fiber. Hence the American Cancer Society recommends a low fat, high fiber diet for Americans.

The judicious use of hormones for therapeutic purposes also can reduce the incidence of some cancers. The widespread use of diethylstilbestrol (DES) to prevent threatened or habitual abortion and premature labor, beginning in the 1940s, eventually resulted in development of vaginal and cervical cancer in a significant number of the female offspring of women who took the drug while pregnant. As was previously mentioned, estrogens prescribed for relief of menopausal symptoms have been implicated in cancer in women. It is recommended that the lowest possible therapeutic dose be given to relieve the symptoms of menopause and prevent osteoporosis.

Cancer of the skin and malignant melanoma are related to prolonged exposure to the ultraviolet radiation in sunlight. The incidence of cancer of the skin is increasing in those persons who value a deep suntan and spend a significant amount of time engaged in outdoor leisure activities. Also at risk are those whose work requires that they be exposed to sunlight for prolonged periods of time, such as farmers.

Since most occupational cancers are preventable, increased awareness on the part of industry and the provision of a safe workplace environment can decrease the incidence of many kinds of cancer. It is also necessary for workers to cooperate with management in reducing exposure to carcinogens by complying with rules for preventive measures.

Ultimately, the prevention of cancer depends upon knowledge of each person's risk factors for development of cancer, and that person's decision to avoid whenever possible those habits and practices that predispose to the disease. There also should be frequent examination and monitoring of those who are known to be at greater risk.
Detection. In addition to routine cancer-related checkups by a health care provider for early detection of cancer, self-examination and awareness of the early danger signs of cancer are suggested as means by which lay persons can participate in detecting it in its earliest stages.

Monthly self-examination of the breast is advocated for all adult women, including those who are postmenopausal. Monthly self-examination of the testes is recommended for all males, particularly those in the age group most at risk for testicular cancer, that is, between the ages of 15 and 34 years.

Another self-administered screening technique is the test for occult blood, a symptom of colorectal cancer. This requires only that a smear of fecal material be applied to a slide, which is sent to a clinical laboratory for examination. To avoid a false positive reading, the person participating in the test is given instructions regarding ingestion of meat and other foods that could interfere with accurate test findings.
Signs of Cancer. There are seven early warning signs of cancer (see table). These signs do not necessarily signify cancer, but should they occur, a health care provider should be consulted and an examination is advisable. Other signs and symptoms depend on location and type of malignancy present.

can·cer (CA),

(kan'ser), Do not confuse this word with canker or chancre.
General term frequently used to indicate any of various types of malignant neoplasms, most of which invade surrounding tissues, may metastasize to several sites, and are likely to recur after attempted removal and to kill the patient unless adequately treated; especially, any such carcinoma or sarcoma, but, in ordinary usage, especially the former.
[L. a crab, a cancer]

can·cer

cancerophobia, carcinophobia.

cancer

/can·cer/ (kan´ser) a neoplastic disease the natural course of which is fatal. Cancer cells, unlike benign tumor cells, exhibit the properties of invasion and metastasis and are highly anaplastic. The term includes the two broad categories of carcinoma and sarcoma, but is often used synonymously with the former.can´cerous
epithelial cancer  carcinoma.

cancer

(kăn′sər)
n.
a. Any of various malignant neoplasms characterized by the proliferation of anaplastic cells that tend to invade surrounding tissue and metastasize to new body sites.
b. The pathological condition characterized by such growths.

can′cer·ous (kăn′sər-əs) adj.

cancer

[kan′sər]
Etymology: L, crab
1 a neoplasm characterized by the uncontrolled growth of cells that tend to invade surrounding tissue and to metastasize to distant body sites.
2 any of a large group of malignant neoplastic diseases characterized by the presence of malignant cells. Each cancer is distinguished by the nature, site, or clinical course of the lesion. The basis of cancer is believed to reside in alterations in deoxyribonucleic acid (DNA), usually at several loci in the genes, but many potential causes are recognized. In men, the most common types of newly diagnosed cancer are the prostate, lung, and colorectal. In women, the most common cancer is breast cancer. Many viruses induce malignant tumors in animals; an infectious cause is likely in some human cancers. An excessive rate of malignant tumors in organ transplantation recipients after immunosuppressive therapy indicates that the immune system plays a major role in controlling the proliferation of anaplastic cells. The incidence of different kinds of cancer varies markedly with gender, age, ethnic group, and geographic location. Cancer is second only to heart disease as a cause of mortality in the United States and is a leading cause of death in children between 3 and 14 years of age. In the United States, common sites for the development of malignant tumors are the skin, lung, prostate, breast, and colon. Surgery remains a major form of treatment, but irradiation is widely used as preoperative, postoperative, or primary therapy; chemotherapy, with single or multiple antineoplastic agents, is often highly effective. Many malignant lesions are curable if detected in the early stage.

cancer

An insidious disease which develops from DNA mutations that alter crucial pathways that normally regulate tissue homeostasis, cell survival and/or cell death.

cancer

Malignancy A malignancy of any embryologic origin, defined by WH Clark, Jr as a '…population of abnormal cells showing temporally unrestricted growth preference (continually increasing number of cells in the population) over normal cells. Such abnormal cells invade surrounding tissues, traverse at least one basement membrane zone, grow in the mesenchyme at the primary site, and may metastasize to distant sites. It is the totality of properties that determines whether a given lesion should be designated as a cancer.' See Actinic cancer, Anal cancer, Apoptosis, Bilateral cancer, Bladder cancer, Bone cancer, Brain cancer, BRCA-related gynecologic cancer, Breast cancer, Burn cancer, Cervical cancer, Chimney sweeps' cancer, Coelomic epithelial cancer, Colorectal cancer, Distant cancer, Early stage breast cancer, Endocrine cancer, Endometrial cancer, Environmental cancer, Epithelial ovarian cancer, Esophagus cancer, Extensive-stage small cell lung cancer, Familial cancer, Gastric cancer, Gynecologic cancer, Head & neck cancer, Hereditary nonpolyposis colorectal cancer, In situ cancer, Infiltrating cancer, Inflammatory breast cancer, Invasive cancer, Interval cancer, Invasive cervical cancer, Islet cell cancer, Kang cancer, Kangri cancer, Khaini cancer, Kidney cancer, Laryngeal cancer, Limited-stage small cell lung cancer, Liver cancer, Localized cancer, Locally advanced cancer, Lung cancer, Major cancer, Meningeal cancer, Microfocal cancer, Minimal breast cancer, Minor cancer, Nonmelanoma cancer, Oral cancer, Nonsmall cell lung cancer, Osteophilic cancer, Ovarian cancer, Pancreatic cancer, Pelvic cancer, Penile cancer, Prostate cancer, Pitch workers' cancer, Radiation-induced cancer, Recurrent cancer, Refractory cancer, Regional cancer, Residual cancer, Scar cancer, Second cancer, Skin cancer, Small cell lung cancer, Solid cancer, Solid cancer, Spontaneous regression of cancer, Terminal cancer, Testicular cancer, Thyroid cancer, Unresectable cancer, Uterine cancer, Vaginal cancer, Virally induced cancer, Yang cancer, Yin cancer, Yin and yang cancer. Cf Carcinoma, Neoplasm, Tumor.

can·cer

(CA, Ca) (kan'sĕr)
General term for malignant neoplasms; carcinoma or sarcoma, especially the former.
[L. a crab, a cancer]

cancer

(kan'ser) [L. cancer, crab, suppurating ulcer]
Enlarge picture
CANCER: (A) Ovarian carcinoma cells and (B) adenocarcinoma of the prostate (orig. mag. ×500)
Malignant neoplasia marked by the uncontrolled growth of cells, often with invasion of healthy tissues locally or throughout the body. Cancer is the second leading cause of death in the U.S. after cardiovascular disease. In 2006 the American Cancer Society (ACS) reported that 564,830 Americans died of cancer and that twice that number were newly diagnosed with one form or another of the disease. The most common cancers in the U.S. are lung, breast, colon, prostate, and skin. Because most cancers occur in patients who are 65 or older, the incidence of cancer is expected to increase as the population ages. More than 200 kinds of cancer have been identified. Cancers that arise from epithelial tissues are called carcinomas; from mesenchymal tissues, sarcomas; from glial cells, gliomas; from lymphatic cells, lymphomas; from blood-forming cells, leukemias; from pigmented skin cells, melanomas; from plasma cells, myelomas. Synonym: malignancy (2) See: carcinoma; leukemia; lymphoma; oncogene; sarcoma

Cancer cells have several reproductive advantages over normal cells. They can make proteins that stimulate their own growth or new blood vessels to bring them nourishment. They can produce enzymes that prevent their chromosomes from aging. They can invade the lymphatic system and bloodstream and find places to grow in new tissues (metastasis).

Usually, as cancer cells proliferate, they become increasingly abnormal and require more of the body's metabolic output for their growth and development. Damage caused by their invasion of healthy tissues results in organ malfunction, pain, and, often, death. See: table (Estimated New Cancer Cases and Deaths by Sex, U.S. 2008)

Etiology

Ionizing radiation, ultraviolet light, some viruses, and drugs that damage nucleic acids may initiate the genetic lesions that result in cancers. The best-known and most widespread type of carcinogen exposure, however, is consumption of tobacco. The ACS estimates that one third of the cancer deaths that occur annually in the U.S. are related to nutrition and other lifestyle factors. Some cancers are familial, i.e., genetic; others result from occupational exposures to carcinogens. Ironically, chemotherapeutic drugs used to treat some cancers may damage chromosomes and occasionally cause secondary malignancies.

Symptoms

Symptoms of widespread cancer include pain, malnutrition, weakness, fatigue, bone fractures, and strokelike syndromes. Early warning signs of cancer may be remembered by the mnemonic CAUTION: Change in bowel or bladder habit; A sore that does not heal; Unusual bleeding or discharge; Thickening or mass in the breast or other body parts; Indigestion or difficulty in swallowing; Obvious change in a wart or a mole; Nagging cough or hoarseness. People should seek prompt medical attention if they observe any of these signs.

Diagnosis

The location of a suspected lesion often dictates the means to diagnose cancer: men with urinary symptoms may be screened for prostate cancer with a prostate specific antigen (PSA) test; an alpha-fetoprotein (AFP) test may be used to screen for liver cancer. Several other tumor markers (such as the CA 125 test for ovarian cancer) are used only after a diagnosis has already been made by other means. Endoscopy and radiography are typically used to locate and assess the extent of the disease, but definitive diagnosis still rests on the examination of cytological specimens (such as the Papanicolaou [Pap] test) or the pathological review of biopsy specimens. See: illustration; table (Controversies in Cancer Screening in the General Population)

Screening for cancers can identify some malignancies before they have invaded neighboring tissues or become widespread. The most widely used screening tests include the Pap test for cervical cancer, mammography for breast cancer, prostate specific antigen tests for prostate carcinoma, and occult blood tests and colonoscopy for intestinal cancers.

Treatment

Surgery, chemotherapy, immunotherapy, hormone therapy, radiation therapy, and combined-modality therapies often are effective methods for treating patients with cancer. The specific treatment used depends on the type, stage, and location of the cancer and the patient's general health.

The pain associated with cancer is often severe. Cancer patients may suffer depression and anxiety and have nutritional deficits. Guidelines addressing these issues are readily available, e.g., from the U.S. Department of Health and Human Services' Agency for Health Care Policy and Research. Publications may be obtained by calling 1-800-4-CANCER or from websites such as from the ACS (www.cancer.org). See: chemotherapy.

Patient care

There must be close collaboration among the entire health care team and the patient and family must be encouraged to participate in care . The patient's knowledge of the disease is determined, misinformation corrected, and information supplied about the disease, its progression, its treatment, and expected outcome. Such information should be updated regularly. The patient's and family's coping mechanisms are supported, and verbalization of feelings and fears, esp. with changes in body image, pain and suffering, and dying and death, is encouraged. Participation in local support groups is encouraged for both patients and families.

Assistance is provided with personal hygiene and physical care as needed. Physical care is directed at the maintenance of fluid and electrolyte balance and proper nutrition. Nutrition is a special concern because tumors compete with normal tissues for nutrients and grow at their expense and because the disease or treatments can cause anorexia, altered taste sensations, mouth ulcerations, vomiting, diarrhea, and draining fistulas. Nutritional support includes assessing the patient's status and problems, experimenting to find foods that the patient can tolerate, avoiding highly aromatic foods, and offering frequent small meals of high-calorie, high-nutrient soft foods along with fluids to limit fatigue and to encourage overall intake. Intake of noncaffeinated liquids should be encouraged: 2 quarts per day of juices or other caloric beverages in frequent, small amounts rather than water alone. Elimination is maintained by administering stool softeners as necessary if analgesic drugs result in constipation.

Using careful and gentle handling, the health care professional assists with range-of-motion exercises, encourages ambulation and mobility, and turns and repositions the immobile patient frequently to decrease the deleterious multisystemic effects of immobilization. The patient is made comfortable by correct body alignment, noninvasive measures (such as guided imagery and cutaneous stimulation), and medication (preferably administered on a regular schedule to prevent pain, with additional dosing to relieve breakthrough pain). Emotional assistance includes allaying the patient's fears of helplessness and loss of control; providing hope for remission or long-term survival but avoiding giving false hope; and providing the patient with realistic reassurance about pain control, comfort, and rest. Psychological counseling and antidepressant therapies may be helpful.

Hospice care (at home or in a dedicated center), if needed, is discussed with the patient and family. The goal is to provide good quality of life with minimal discomfort, pain, and restrictions rather than to continue specific therapy. Family members are encouraged to assume an active role in caring for the patient. Communication is fostered between patient and family and other health care providers, and the patient is helped to maintain control and to carry out realistic decisions about issues of life and death.

To provide effective emotional support to the patient and family, health care professionals must understand and cope with their own feelings about terminal illness and death and seek assistance with grieving and in developing a personal philosophy about dying and death. They will then be better able to listen sensitively to patients' concerns, to offer genuine understanding and comfort, and to help patients and family work through their grief.

bladder cancer

A malignancy that arises in the cells of the urinary bladder. In Western nations, most of the cases are transitional cell carcinomas. Common causes include cigarette smoking, occupational exposure to carcinogens, or chronic bladder infection. Symptoms of bladder cancer may include painful urination, bloody urination, or frequent or urgent urination. Depending on the extent of invasion or spread of the tumor, it may be treated with endoscopy, surgery, chemotherapy, or immunotherapy.

bone cancer

Any malignancy of bone tissue. Primary bone tumors (such as osteosarcomas) are rare in adults; they are seen more often in children and adolescents. Secondary or metastatic bone tumors are far more common. Tumors arising in other areas of the body that metastasize to the bones most often spread from organs such as prostate or breast.

breast cancer

See: breast cancer

cervical cancer

A malignant neoplasm of the cervix of the uterus. With an incidence of 15:100,000, it is the third most common cancer of the female reproductive tract and causes 5% of all cancer deaths among women. Although it may occur in younger women, the average age at diagnosis is 54. The disease is insidious, asymptomatic in the early stages, and best treated when recognized at an early stage.

Etiology

Some strains of the human papillomavirus (HPV) are carcinogenic to cervical epithelium. While there are other risk factors (such as tobacco smoking, early age at first intercourse, and having multiple sex partners), HPV is the major factor responsible for the development of this cancer.

Diagnosis

Periodic Pap tests are recommended for all sexually active women. The tests identify cellular changes with 95% accuracy. Dilatation and curettage, punch biopsy, and colposcopy may be done if Pap test findings raise the suspicion of cancer. If abnormal cells are detected, HPV testing is often performed to screen for presence of one of the high risk types of the virus. See: Bethesda System, The; cervical intraepithelial neoplasia; colposcopy; cryosurgery; loop electrode excision procedure; Papanicolaou test

Treatment

Management varies from cryotherapy or laser therapy for low-grade squamous intraepithelial lesions, conization for carcinoma in situ, to hysterectomy for preinvasive cervical cancer in women who are not planning to have children. Stage-related management of invasive cervical carcinoma includes radiation and/or hysterectomy.

Prevention

Vaccination against human papillomavirus virus (HPV).

See: HPV vaccine.

chimney sweeps' cancer

Cancer of the skin of the scrotum due to chronic irritation by coal soot.

colorectal cancer

Abbreviation: CRC
A malignancy of the colon or rectum. It is the second leading cause of cancer deaths in the U.S. At some time during their lives 6% of Americans will be diagnosed with the disease. In 2008 the ACS estimated that 154,000 Americans would be newly diagnosed with colorectal cancer and that it would cause 50,500 deaths.

Etiology

The cancer occurs more often in people with a family history of the disease, those with familial adenomatous polyposis, and in those with inflammatory bowel diseases such as ulcerative colitis. It also occurs more often in people who are obese than in those who are not and in those who consume a high fat, low-fiber diet.

Symptoms

Symptoms may be absent or may include change in the usual pattern of bowel habits, esp. in those over 40; recent onset of constipation, diarrhea, or tenesmus in an older patient; bright red or dark blood in the stool. Laboratory findings may include iron-deficiency anemia or positive fecal occult blood tests.

Diagnosis

Diagnosis may be suggested by findings on digital rectal examination, anoscopy, flexible or rigid sigmoidoscopy, colonoscopy, virtual colonoscopy, or barium enema examination. It is confirmed by biopsy of suspicious lesions. Prevention includes screening of asymptomatic men and women of average risk starting at age 50, annual home fecal occult blood testing (over a three-day period), and colonoscopy every 10 years. During colonoscopy, removal of benign polyps prevents progression to malignant tumors. If polyps are found, colonoscopy should be repeated in 3 to 5 years (depending on the presence of other risk factors). Detection of colorectal cancer at an early stage via colonoscopy offers patients a very high likelihood of cure rate at 5 years. Neither digital rectal examination nor testing of a single stool specimen from the digital exam provides adequate screening. Patients at increased risk for colorectal cancer (those who have had previous colorectal adenomas or resected cancers or a history of ulcerative colitis or of colon cancer in a first-degree relative younger than 60) should undergo screening more frequently and at an earlier age. When colorectal carcinoma is diagnosed, additional tests are conducted to determine the stage of the disease (chest radiographs, CT, MRI, and blood studies, including carcinoembryonic antigen levels, and liver function studies).

Treatment

Surgical resection performed by laparotomy, minimally invasive surgery, microsurgery, or laparoscopy can cure localized colorectal cancer. Whatever procedure is used, the type of surgery depends on the location of the tumor, and the goal of the surgery is removal of the malignant tumor and adjacent tissue and any lymph nodes that may contain cancer cells. Adjuvant therapies may include chemoembolization of blood vessels that feed the primary tumor or metastases; radiation therapy; brachytherapy; chemotherapy; or monoclonal antibody therapy. Carcinoembryonic antigen is helpful in monitoring patients during and following treatment to determine effectiveness and detect recurrence or metasasis.

Patient care

Health care providers should teach patients the importance of colorectal screening and indicate applicable lifestyle modifications (a low-fat diet, maintenance of a normal body mass index). Patients with familial colon cancer syndromes, such as familial adenomatous polyposis, should be counseled about the need for close surveillance by professional gastroenterologists.

Aspirin and other nonsteroidal anti-inflammatory drugs appear to reduce the number of colon polyps, thus decreasing the risk of developing colorectal cancer. Patients interested in such therapy should discuss its potential risks and benefits with their health care providers.

Patients diagnosed with colorectal cancer who undergo surgery need counseling about the operation, the duration of recovery, and, in many cases, the use of a postoperative colostomy . Before surgery, a stomal therapist consults with the surgeon regarding appropriate stoma location, and the abdomen is marked. The therapist answers questions from the patient and family and begins to develop a relationship that will support the patient through postoperative care and teaching. Patient and family are encouraged to access the ACS (800-ACS-2345 or www.cancer.org) for additional information.

Synonym: carcinoma of the colon; colorectal carcinoma

epithelial cancer

Basal cell carcinoma.

epithelial cancer of the ovary

See: ovarian cancer

esophageal cancer

See: esophageal cancer

fallopian tube cancer

A malignancy that begins to grow in the cells that form the inner surfaces of the fallopian tubes, usually an adenocarcinoma. It is the least common form of gynecological cancer.

familial medullary thyroid cancer

Abbreviation: FMTC
A rare, autosomal, dominantly inherited predisposition to medullary carcinoma of the thyroid. The disease is genetically related to the multiple endocrine neoplasia (MEN) syndromes. However, families affected by FMTC rarely develop hyperparathyroid tumors or pheochromocytoma.

gastric cancer

Adenocarcinoma of the stomach. About 50% to 60% of all carcinomas of the stomach occur in the pyloric region. About 20% occur along the lesser curvature; the rest are located in the fundus, particularly along the greater curvature. Although this form of cancer is common throughout the world in people of all races, the incidence of gastric cancer exhibits unexplained geographic, cultural, and gender differences, with the highest incidence in men over 40 and higher mortality in China, Korea, Japan, Taiwan, Iceland, Chile, and Austria.

From 1930 to the 1990s, the incidence of gastric cancer declined from about 38 cases per 100,000 to about 6 cases per 100,000. In 2010, the ACS estimated there would be 21,000 new cases of gastric cancer in the U.S. and 10,570 deaths from this disease. The prognosis for a particular patient depends on the stage of the disease at the time of diagnosis, but overall the 5-year survival rate is about 19%.

Predisposing Causes

Although the cause of gastric cancer is unknown, predisposing factors include a diet rich in pickled or smoked foods, a history of gastric surgery, and a history of infection by Helicobacter pylori. The disease runs in some families; therefore, there may also be a genetic component.

Complications

Malnutrition occurs as a result of impaired eating, the metabolic demands of the growing tumor, or obstruction of the GI tract. Iron deficiency anemia results as the tumor causes ulceration and bleeding. The tumor can interfere with the production of the intrinsic factor needed for vitamin B12 absorption, resulting in pernicious anemia. As the cancer spreads to regional lymph nodes and nearby structures and metastasizes to other structures, related complications occur.

Signs and Symptoms

In the early stages, the patient may occasionally experience pain in the back or in the epigastric or retrosternal areas that is relieved with nonprescription analgesics. As the tumor grows, the patient may notice a vague feeling of fullness, heaviness, and abdominal distention after meals. Depending on the progression of the cancer, the patient may report weight loss due to disturbance of the appetite; nausea; and vomiting. There may be dysphagia and coffee-ground vomitus if the tumor is located in the cardia and slowly bleeds. Weakness and fatigue are common. Because early symptoms include chronic dyspepsia and epigastric discomfort, patients may self-treat with OTC antacids or histamine blockers, delaying prescribed therapies and allowing the cancer to progress.

Palpation of the abdomen may disclose a mass. A skilled examiner may be able to palpate enlarged lymph nodes, esp. in the supraclavicular and axillary regions.

Diagnostic Studies

Gastric cancer is diagnosed by fiber-optic endoscopy with biopsy. Studies to rule out specific organ metastases include endoscopic ultrasonography, computed tomography scans, chest radiographs, liver and bone scans, and liver biopsy.

Treatment

Radical surgery to remove the tumor is possible in more than one third of patients. Even in the patient whose disease is not considered surgically curable, resection may temporarily ease symptoms and improve the patient’s response to chemotherapy and radiation therapy. The nature and extent of the lesion determine the type of surgery. Surgical procedures include gastroduodenostomy, gastrojejunostomy, partial gastric resection, and total gastrectomy. If metastasis has occurred, the omentum and spleen may have to be removed.

Chemotherapy for GI tumors may help control signs and symptoms and prolong survival. Gastric adenocarcinomas respond to several agents, including fluorouracil, carmustine, doxorubicin, and mitomycin. Tumors that express HER2 antigens respond to treatment with trastuzumab (a monoclonal antibody that targets the human epidermal growth factor). Antispasmodics, antacids, and proton pump inhibitors may help relieve GI acidity and reflux symptoms. Antiemetics can control nausea, which intensifies as the tumor grows. Analgesics, sedatives, and tranquilizers are used to control pain and anxiety.

Patient care

Nutritional intake is monitored, and the patient is weighed periodically. The health care provider initiates comprehensive clinical and laboratory investigations, including serial studies as indicated, if these have not already been done. The patient is prepared physically and emotionally for surgery, chemotherapy, or radiotherapy. During hospitalization, all general patient care concerns apply.

Throughout the course of the illness, a high-protein, high-calorie diet with vitamin supplementation helps the patient avoid or recover from weight loss, malnutrition, and anemia, and promote wound healing. Frequent small meals are offered.

To stimulate a poor appetite, antidepressant or steroid drugs may be administered. The patient is instructed in use of all drugs and the expected adverse effects of treatment, as well as in management strategies for these effects.

Radiation therapy may cause nausea, vomiting, local skin damage, malaise, diarrhea, and fatigue. Chemotherapy may cause bone marrow suppression, infection, nausea, vomiting, mouth ulcers, and hair loss. During radiation or chemotherapy, oral intake is encouraged to remove toxic metabolites. Bland fruit juices, ginger ale, or other fluids, and prescribed antiemetics are provided to minimize nausea and vomiting; comfort and reassurance are offered as needed. The patient is advised to report persistent adverse reactions.

The patient is encouraged to follow a normal routine as much as possible after recovery from surgery and during radiation therapy and chemotherapy. He should stop activities that cause excessive fatigue (at least temporarily) and incorporate rest periods. The patient should avoid crowds and people with known infections. Home-health care is provided as necessary. If curative treatment fails, palliative care and psychological support continues, with questions answered honestly but tactfully. Home or in-patient hospice care referrals are suggested as available.

Synonym: stomach cancer

hard cancer

A cylindrical cancer composed of fibrous tissue. Synonym: scirrhous cancer; scirrhous carcinoma

head and neck cancer

Squamous cell carcinoma usually arising in the pharynx, oral cavity, or larynx. Research has shown links between human papillomavirus infection, tobacco smoking, and excessive alcohol use and head and neck cancers.

interval cancer

A cancer whose presence is diagnosed in the time between scheduled screening tests, e.g., a breast cancer that is not detected by regular periodic mammography, professional examination, and self-breast exams.

kidney cancer

Renal cell carcinoma.

latent cancer

A cancer that grows slowly and has no important health effect on the patient.

lip cancer

A squamous cell carcinoma of the lower lip usually seen in men or smokers.

liver cancer

Malignancy of the liver that results either from spread from a primary source or from primary tumor of the liver itself. The former is the more frequent cause. Male sex, hepatitis B or C, cirrhosis, and other liver diseases are predisposing factors. The liver is the most common site of metastatic spread of tumors that disseminate through the bloodstream. The prognosis for survival is from a few months to 1 yr.

Symptoms

The disease may cause severe pain and tenderness; cachexia (loss of weight); and encephalopathy. Jaundice is common. The liver is enlarged, its surface is nodular, and a central depression or umbilications can often be detected.

Enlarge picture
LUNG CANCER: Lung cancer seen endoscopically. The tumor is bleeding after being biopsied.

lung cancer

The deadliest form of cancer in the U.S., responsible for about 159,000 deaths a year, according to statistics published by the ACS in 2011. The term includes four cell types: squamous cell (epidermoid) carcinoma, adenocarcinoma, large cell (anaplastic) cancer, and small cell (oat cell) cancer. The vast majority are caused by carcinogens in tobacco smoke, including second-hand smoke. Other risks include exposure to carcinogenic industrial and air pollutants (asbestos, uranium, arsenic, nickel, chromium, iron oxides, coal dust and radioactive dusts), radon gas concentrations, and familial susceptibility. Survival after diagnosis is poor: only one of seven patients lives for 5 years. However, if detected early (before spreading from the lungs), survival rates rise for most people. Radiofrequency ablation (RFA) is a promising therapy for patients with small lung tumors. Synonym: bronchogenic carcinoma See: illustration

Treatment

Treatment includes lung surgery, radiation therapy, and chemotherapy usually in combination.

Patient care

Staging determines the extent of the disease and aids in planning treatment and predicting the prognosis. Lung cancer is relatively difficult to cure but much easier to prevent. Children and adolescents should be discouraged from smoking tobacco products, and current smokers should be assisted in their efforts to quit, e.g., through referrals to local branches of the ACS, smoking-cessation programs, individual counseling, or group therapy.

Screening and Public Health

Chest x-rays do not show small, early cancers, but CT scanning can be used to screen people who have a long history of smoking and who are 50 to 60 years old. In this high-risk group, screening detects the disease in its early stages when it is most likely to be curable. However, since screening is very expensive, and since there are millions of smokers, the public health costs of mass screening are high compared with the cost of encouraging smokers to quit or of teaching teenagers not to start smoking.

oral cavity cancer

Squamous cell carcinoma of the mouth or tongue. Oral cavity cancers are only rarely caused by salivary gland tumors or sarcomas.

ovarian cancer

Any malignant growth in an ovary. About 85% to 90% of ovarian cancers arise from the surface epithelium of the ovary. In the U.S. in 2008, the ACS estimated there would be about 21,600 new patients diagnosed with ovarian cancer and about 15,200 deaths from the disease. Most cases (70%) are diagnosed when the disease is already at an advanced stage because early detection methods are still unsatisfactory. The early symptoms of the disease are often nonspecific and often mimic irritable bowel (constipation, vague abdominal pain, bloating). Initial laboratory studies (routine blood tests and x-rays) are often unremarkable.

Currently, more women die of epithelial ovarian cancer than of all other gynecological cancers combined. A small percentage of patients with ovarian cancer may have a hereditary predisposition, e.g., they have BRCA-1 or BRCA-2 genes. High-risk women include those with multiple first-degree relatives (mother, sister, daughter) or second-degree relatives (aunt, grandmother, cousin) with histories of breast or ovarian cancer. Preventive surgery to remove the ovaries and fallopian tubes is the only way such women can significantly reduce their risk.

Patient care

Ovarian cancer patients may feel threatened or vulnerable. They benefit from pretreatment support and education. Health care professionals address the patient's psychosocial needs while preparing her for treatment and manage the potential adverse reactions and the treatment and changes related to advancing disease.

The first step in care is typically surgical debulking of the tumor. In this phase of care, the surgical oncologist attempts to remove not only the primary tumor, but also as many small tumorlets found within the peritoneum. The patient and family should be taught about the extensive surgical procedure and what to expect after surgery. After surgery, the patient is monitored for infection, circulatory complications, fluid and electrolyte imbalances, and pain. The patient who is to receive chemotherapy should be taught about major adverse reactions to the usual medications employed, taxanes and platinum-based drugs, such as fatigue, nausea and vomiting, hair loss, diarrhea, constipation, mucositis, neuropathy, arthralgia and myalgia, difficulty concentrating (chemobrain), and myelosuppression, as well as about measures to be taken to prevent and manage these problems. Chemotherapy may be given directly into the peritoneum or intravenously. Depression, anger, frustration, and anxiety are common.

After the acute phase of treatment, the patient may undergo premature menopause; loss of fertility; alterations in body image, sexual function, and family relationships; impaired functional capacity; financial difficulties; and loss of spiritual well-being. The patient should be assessed for mood changes, inability to concentrate, fatigue, insomnia, and other symptoms of depression. Her medical history, current medications and treatments, nutritional status, pain rating, elimination pattern, and sexual history should be reviewed for factors that contribute to depression. Participating in a support group, meeting with mental health professionals, and taking an antidepressant or anti-anxiety medication can help alleviate depression and anxiety.

Advancing or relapsing ovarian cancer may cause complications. These may include development of ascites, intestinal obstruction, deep vein thrombosis, malnutrition and cachexia, lymphedema, and pleural effusion. Current five-year survival rates for ovarian cancer are about 30% to 40%. If ovarian cancer recurs after treatment or fails to regress with treatment, palliative and end-of-life care may aid both patients and their families.

cancer of the pancreas

Pancreatic cancer.

pancreatic cancer

Carcinoma of the pancreas. The American Cancer Society estimated there would be 37,700 new cases of the disease in the U.S. in 2008, with 34,300 deaths caused by the illness that year. Although the causes of pancreatic cancer are unknown, it has been found in more men than women, more blacks than whites, more smokers than nonsmokers, and more patients with a history of chronic pancreatitis and diabetes mellitus than without. When cancer occurs in the head of the pancreas, where it may obstruct the bile ducts and cause jaundice, the disease is most likely to be diagnosed at an early stage, when it may be most responsive to therapy. Surgical excision of the tumor and treatment with chemotherapy or radiotherapy may prolong survival in some patients. Only 4% of victims of pancreatic cancer survive 5 years. Synonym: carcinoma of the pancreas; cancer of the pancreaspancreatic carcinoma

primary cancer

The original cell or tissue type from which a metastatic cancer arises.

prostate cancer

See: prostate cancer

scirrhous cancer

Hard cancer.

skin cancer

A broad term that includes basal cell carcinomas, squamous cell carcinomas, and melanomas. Together, these skin cancers are the most common cancers in the U.S. They are all associated with excessive exposure to ultraviolet light, e.g., sun exposure. See: basal cell carcinoma; squamous cell carcinoma; melanoma

Patient care

According to the U.S. Preventative Services Task Force (USPSTF), benefits from routine screening for skin cancers with a total body skin examination are unproven, even in high-risk patients.

stomach cancer

Gastric cancer.

terminal cancer

Widespread or advanced cancer, from which recovery is not expected.

testicular cancer, germ-cell

Any of a group of testicular cancers that include choriocarcinomas, embryonal carcinomas, seminomas, spermatocytic seminomas, sex cord tumors, teratomas, and tumors with mixtures of several different malignant cell types.

cancer of unknown primary site

Disseminated cancer in which the original tissue type is uncertain. Such cancers generally have poor prognoses.

Etiology

Patients with such cancers are usually evaluated for tumors that might respond well to therapy, such as a lymphoma, a thyroid cancer, a germ cell tumor, or neoplasms of the breast or prostate.

cancer of uterus

A malignant neoplasm of the uterus, usually of the endometrium, found most often in women over 50. Other uterine cancers include those that arise in the muscular wall of the uterus (sarcomas), cervical cancers, and trophoblastic cancers. Symptoms may include post menopausal bleeding, bleeding between periods, and irregular, long, heavy periods. Pain during urination and during intercourse may be reported. Diagnosis of endometrial cancer is made by endometrial biopsy. The most common treatment is hysterectomy, although radiation and hormone therapy may be used. See: Bethesda System, The; cervical cancer; cervical intraepithelial neoplasia

vulvar cancer

Any malignant neoplasm of the vulva. Of these, 90% are squamous cell carcinomas; the rest are caused by adenocarcinomas, sarcomas, or Paget's disease.

Vulvar cancer accounts for 4% of all gynecological malignancies. More than 50% of cases occur in postmenopausal women between 65 and 70. Generally, vulvar cancers are localized, slow-growing, and marked by late metastasis to the regional lymph nodes. Treatment may include surgery and/or radiation therapy. See: vulvectomy

*Excludes basal and squamous cell skin cancers and in situ carcinomas except urinary bladder. Carcinoma in situ of the breast accounts for about 67,770 new cases annually, and melanoma in situ accounts for about 54,020 new cases annually. Estimates of new cases are based on incidence rates from the NCI SEER program, 1995 to 2004. SOURCE: ©2008, American Cancer Society, Inc., Surveillance Research
Estimated New CasesEstimated Deaths
MaleFemaleMaleFemale
All sites745,180692,000294,120271,530
Oral cavity & pharynx25,31010,0005,2102,380
Esophagus12,9703,50011,2503,030
Stomach13,1908,3106,4504,430
Colon & rectum77,25071,56024,26025,700
Liver & intrahepatic bile duct15,1906,18012,5705,840
Pancreas18,77018,91017,50016,790
Lung & bronchus114,690100,33090,81071,030
Melanoma-skin34,95027,5305,4003,020
Breast1,990182,46045040,480
Uterine corpus40,1007,470
Ovary21,65015,520
Prostate186,32028,660
Urinary bladder21,23017,5809,9504,150
Kidney & renal pelvis33,13021,2608,1004,910
Brain & other nervous system11,78010,0307,4205,650
Thyroid8,93028,410680910
Non-Hodgkin lymphoma35,45030,6709,7909,370
Leukemia25,18019,09012,4609,250
*Note: Cancer screening tests are most likely to be useful when: (1) the cancer is common and deadly; (2) the test reliably distinguishes between healthy and diseased people; (3) early detection of the disease leads to improved treatments; (4) treatments are safe and well-tolerated; (5) the psychological effects of test results are addressed sensitively and carefully; (6) the tests are applied to people who will truly benefit from them.
TestTo DetectDiscussion
Breast self-examinationBreast cancerMonthly self-examination by women is a noninvasive way to screen for changes in the breast. This method detects many benign and cancerous lumps, but its ability to prolong life is still debated.
MammographyBreast cancerMammography is clearly effective screening in women over 50. Most mammograms are obtained by women in their 40s. The incidence of cancer is higher in later life, when mammography use tends to decline.
Digital rectal examination (DRE)Colorectal cancer, prostate cancerDRE is easy to perform and inexpensive but its cancer screening value is unproven; and, when it detects cancers, there is no proof that the test results in better patient outcomes. In addition, DRE detects a very small number of cancers, only those within the reach of the examiner.
Fecal occult blood testColorectal cancerIn people over 50, testing stool specimens for hidden bleeding detects many cancers; this detection results in earlier treatment and prolongation of life. The accuracy and value of the test relative to sigmoidoscopy and colonoscopy are uncertain.
Chest x-ray, sputum cytology, CT of the chestLung cancerProspective studies have yielded conflicting results for any method of screening for lung cancer in smokers, and the costs of screening, e.g., with computed tomography of the chest, may be prohibitive. The tests are of no value to nonsmokers.
Prostate specific antigen (PSA)Prostate cancerPSA testing detects many previously undetected prostate cancers but may result in increased death and disease due to complications from subsequent surgery. Refinements in its application may improve its usefulness as a screening tool.
Genetic testingFor predisposition to a variety of cancersThe predictive value of genetic testing for cancer is very small. Experts are debating the emotional and ethical consequences of genetic cancer screening tests.

cancer

A disease of DNA. The term is used by the medical profession as a convenient and comprehensive label for all forms of MALIGNANT growths. There are two broad classes of cancers—those which arise from surface linings (CARCINOMAS) and those which arise from solid tissues (SARCOMAS). Cancers spread by local invasion and by lymph and blood spread (METASTASES) and their degree of malignancy is a measure of the rapidity with which they spread. It has long been believed that cancers start either as the result of small genetic changes to genes called tumour suppressor genes that restrain the ability of cells to divide, or to genes called oncogenes which suffer mutations. Research now suggests that many other abnormalities are probably involved. In early cancers there is much disruption of the chromosomes, some of which are duplicated or lost or truncated and parts fused together. Chromosomal instability appears to be an important element. It is only a matter of time before cancers are classified by their pattern of gene abnormality. Although some aspects of the biology of cancers remain obscure, recent years have shown remarkable advances in the effective treatment of many cancers. See also CANCER STEM CELLS.

cancer

a disease affecting the growth rate of affected tissues, in which the control mechanisms of cells become altered and the cells divide to form neoplastic growths or tumours. ‘Benign’ tumours consist of well-differentiated cells similar to those in the surrounding tissues and are usually harmless unless located in regions where no operation is possible. ‘Malignant’ tumours are dangerous and usually contain embryonic cells, which are capable of floating away and forming new malignant growths in other sites.

Little is known of the cause of cancer, though exposure to CARCINOGENS such as nicotine and mustard gas or the presence of certain microorganisms are possible causes. Radiation, surgery and chemotherapy are all used in the treatment of cancers.

cancer

; Ca any of various types of malignancy, or neoplasm showing signs of malignancy (i.e. local tissue invasion, metastasis formation and recurrence after apparent cure)

cancer,

n any of a diverse group of malignant neoplastic disorders characterized by uncontrolled cell growth in various sites throughout the body. Cancer is the second leading cause of death in the United States, after heart disease.
cancer staging,
n prognostic tool for cancer treatment where a malignant tumor is charted with respect to its size and location in the patient's body.

can·cer

(CA) (kan'sĕr)
General term frequently used to indicate any of various types of malignant neoplasms, most of which invade surrounding tissues, may metastasize to several sites, and are likely to recur after attempted removal and kill the patient unless adequately treated.
[L. a crab, a cancer]

cancer (kan´sur),

n a malignant neoplasm. The term is sometimes incorrectly used to include any neoplasm, whether benign or malignant.
Carcinoma and
sarcoma are more specific terms.
cancer, oral,
n malignancies indicative of unchecked cell growth that are mainly found in and around the oropharynx, gingiva, floor of the oral cavity, lower lip, and base of the tongue.

cancer

any malignant, cellular tumor.
The term cancer encompasses a group of neoplastic diseases in which there is a transformation of normal body cells into malignant ones. This probably involves some change in the genetic material of the cells, deoxyribonucleic acid (DNA), perhaps as a result of faulty repair of damage to the cell caused by carcinogenic agents or ionizing radiation. The altered cells pass on inappropriate genetic information to their progeny cells and begin to proliferate in an abnormal and destructive way. Normally, the cells of which body tissues are made are regularly replaced by new growth, which stops when the cells are replaced; new cells form to repair tissue damage and stop forming when healing is complete. Why they stop forming is unknown, but clearly the body in its normal processes regulates cell growth. In cancer, cell growth is unregulated.
As the cancer cells continue to proliferate, the mass of abnormal tissue that they form enlarges, ulcerates, and begins to shed cells that spread the disease locally or to distant sites. This migration is called metastasis. Some cells invade neighboring tissues, destroying and displacing normal cells and taking their place. Others can enter the blood and lymphatic vessels and are carried along in the fluid to other parts of the body. Another way in which malignancy can be spread is by entering a body cavity by diffusion and coming in contact with a healthy organ.
See also tumor, neoplasm, neoplasia. For individual cancers see under specific types. Cancers of specific organs or tissues are not listed.

Patient discussion about cancer

Q. how many types of cancer are they?

A. There are over 200 different types of cancer. You can develop cancer in any body organ. There are over 60 different organs in the body where you can get a cancer.

Each organ is made up of several different tissue types. For example, there is usually a surface covering of skin or epithelial tissue. Underneath that there will be some connective tissue, often containing gland cells. Underneath that there is often a layer of muscle tissue and so on. Each type of tissue is made up of specific types of cells. Cancer can develop in just about any type of cell in the body. So there is almost always more than one type of cancer that can develop in any one organ.

Q. why does it call "cancer"?can you treat cancer?

A. the name came from the appearance of the cut surface of a solid malignant tumour, with the veins stretched on all sides as the animal the crab has its feet, whence it derives its name. Hippocrates first called it in that name after describing few types of cancer.
some of the cancers are treatable but that is a big subject. there are some very nice videos here on the site that can give you a clue about that. just search them there ^ :)

Q. Cancer - incurable? When i was surfing the internet for the incurable disease, i found CANCER is one among them. Is there not a medicine found yet? Really is it incurable?

A. I like to share with you what i read from a book it said 'With modern day treatments many cancers are completely cured but unfortunately there are still many others which are not.

Although it is not always possible to be certain, doctors are often able to tell whether or not a particular cancer might be cured. Even if cancer is incurable they will usually still offer treatment in the hope of prolonging life and, controlling, symptoms.'
http://www.youtube.com/watch?v=FOBvDTf9ohQ

More discussions about cancer
References in periodicals archive ?
An easier system would allow different experts to develop a great variety of possible news feeds--such as vaccines, AIDS-related cancers, treatment news for resource-limited settings, of basic-science issues.
These worldwide frequencies and disease results suggest that CCR5-[DELTA]32, CCR2-64I, and SDF1-801A are good candidates for protection against additional infectious agents, AIDS-related cancers, and non-AIDS-related cancers.
The incidence of AIDS-related cancers is falling among people infected with HIV while other cancers are increasing in this population, according to a study from the Centers for Disease Control and Prevention and the National Cancer Institute.
This unique event, produced by Asman & Associates, raises money for The USC/Norris Comprehensive Cancer Center, which offers the most advanced cancer treatment available for cancer of the genitourinary, central nervous and female reproductive systems; breast, lung and gastrointestinal tract, as well as melanoma, leukemia, lymphomas and AIDS-related cancers.