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Mesothelioma is an uncommon disease that causes malignant cancer cells to form within the lining of the chest, abdomen, or around the heart. Its primary cause is believed to be exposure to asbestos.
Malignant mesothelioma is also known as asbestos cancer or simply "meso." Mesothelioma causes cancerous cells to develop in the body's mesothelium, where they can spread to and damage vital organs and tissue. These malignant cells can also metastasize to other regions of the body. Mesothelioma is very difficult to diagnose and responds poorly to most treatment modalities, accounting for a poor prognosis.
The disease derives its name from the mesothelium, a sac-like membrane that protects most of the body's internal organs. It is divided into two distinct protective layers of cells: the visceral (the layer directly surrounding the organ) and the parietal (a sac around the body cavity). By releasing a lubricating fluid, the mesothelium allows the organs to move more freely within the body cavity; for example, the contraction and expansion of the lungs. The mesothelium is also referred to according to where it is located in the body: pleura (chest), peritoneum (abdomen), and pericardium (heart).
Over two-thirds of all mesothelioma cases begin in the pleura region. Pleural mesothelioma spreads through the chest cavity, occasionally developing in the lungs as well. The disease most commonly causes pleural effusion, an excess build-up of fluid inside the chest cavity. This excess fluid increases pressure on the lungs and restricts breathing. In addition, malignant cells can cause the pleural lining to thicken and restrict the breathing space even further.
Peritoneal mesothelioma is the second most common form of the disease, accounting for less than 30% of all cases. Malignant cells form in the peritoneum, affecting the abdomen, bowel, liver, and spleen. Similar to pleural mesothelioma, the disease also causes a build up of excess fluid in the abdominal cavity. Normal bodily functions, such as digestion, can be hindered by the obstruction of organ movement.
Very rare forms of mesothelioma occur in the pericardium, as well as the mesothelium of the male and female reproductive organs. Cystic mesothelioma of the peritoneum, another rare form of the disease, occurs predominantly in women and is more benign in nature.
Malignant mesothelioma takes the form of one of three cell-types: epithelioid (50% to 70% of cases), sarcomatous (7% to 20% of cases), and biphasic/mixed (20% to 35% of cases). Of these cell-types, epithelioid mesothelioma carries the most favorable prognosis, followed by biphasic, and finally sarcomatous (very aggressive).
Mesothelioma remains relatively uncommon in the United States, with approximately 2,500 new cases reported annually. The incidence rates are much higher in Western Europe (over 5,000 cases reported annually). These numbers are expended to climb dramatically over the next 20 years. Older males (median age 60 at diagnosis) are three to five times more likely to develop mesothelioma than women. This is most like do to male predominance in those professions with an increased risk of asbestos exposure.
Causes & symptoms
Approximately 80% of all mesothelioma patients have a history of asbestos exposure. The majority of these patients were employed in an industry that involved the use of asbestos in some fashion. In addition to occupational exposure, household exposure of family members is not uncommon. An exposed individual can carry the asbestos particles on their clothing, skin, and in their hair when they return home, resulting in paraoccupational exposure. Even brief exposure to asbestos, as little as one to two months, can result in long-term consequences. Although the dangers of asbestos have been known for decades, the long latency period of mesothelioma (30 to 40 years) means that majority of patients were already exposed as far back as the 1950s. It is estimated that up to eight million Americans have already been exposed. Several industries, in particular, show a higher incidence of asbestos exposure:
- Insulators (Asbestos workers)
- Steel workers
- Maintenance workers
- Brake mechanics
Mesothelioma is very aggressive once it truly takes hold. However, its initial symptoms are generally non-specific in nature and/or mimic other conditions, such as persistent pneumonia or gastronomical disorders. Some patients will exhibit no symptoms at all. As such, proper evaluation and diagnosis are commonly delayed and must be confirmed by a doctor.
Patients suffering from pleural mesothelioma most commonly exhibit signs of dyspnea, pleural effusions, and/or chest pain. The majority of pleural effusion symptoms will exhibit in the right lung (60% of the time). Patients may also exhibit persistent cough, weight loss, weakness, fever, and difficulty swallowing.
Patients suffering from peritoneal mesothelioma most commonly exhibit signs of pain and/or swelling in the abdomen from fluid retention or tumor growth. Weight loss, nausea, bowel obstruction, anemia, fever, and swelling in the legs and/or feet are also known symptoms.
Only a physician can properly diagnose mesothelioma. A review of the patient's medical history, including any past exposure to asbestos, should be conducted for any patient displaying dyspnea, chest pain, fluid build-up, or pain and/or swelling in the abdomen. This review is followed up with a complete physical examination, which should involve the use of imaging techniques. X rays, computed tomography (CT) scans, and magnetic resonance (MRI) scans of the chest and/or abdomen, as well as lung function, can provide the doctor with critical diagnostic information. Although positron emission tomography scans are expensive and not covered under most insurance, this diagnostic tool has proven very useful in determining tumor sites and staging of the disease.
If indicated, the doctor may wish to internally examine the patient's chest and/or abdominal cavity. These diagnostic procedures, known as thoracoscopy (chest) and peritoneoscopy (abdomen), are usually conducted in a hospital setting. Both procedures involve a fiber-optic imaging tool being inserted into the patient through an incision. These endoscopic tools will provide the doctor with a closer look at the body cavity, and any abnormal tissue or fluid build-up found therein. Excess fluid can be suctioned out through a needle or tube, in a process known as thoracentesis (for the chest) or paracentesis (for the abdomen). Additionally, the doctor may perform a biopsy of any abnormal tissue they discover during this time. Pathological examination of abnormal tissue, as well as fluid, remains the only effective method of confirming the diagnosis of mesothelioma. Biopsy will also assist the doctor in properly staging the disease's progression.
Once a confirmation of malignant mesothelioma has been established, the doctor will conduct further tests to determine the extent to which the primary disease has spread. This diagnostic process is known as "staging." Malignant pleural mesothelioma of can be broken into four stages:
- Localized Malignant Mesothelioma (Stage 1)—Cancer is present in the right or left pleura. May involve the lung, the pericardium, or diaphragm on that side.
- Advanced Malignant Mesothelioma (Stage 2)—Cancer has spread beyond the right or left pleura to lymph nodes on that side. May involve the lung, the pericardium, or diaphragm on that side.
- Advanced Malignant Mesothelioma (Stage 3)—Cancer has spread into the chest wall, diaphragm, ribs, heart, esophagus, or through the abdominal lining. Nearby lymph nodes may or may not be involved.
- Advanced Malignant Mesothelioma (Stage 4)—Cancer shows evidence of metastasis or spread through the bloodstream to distant organs and/or tissues.
Recurrent malignant mesothelioma may also occur, where the cancer returns in its original location or elsewhere in the body even after treatment.
There are three traditional treatment modalities for mesothelioma: surgery, radiation therapy, and chemotherapy. The location and the stage of the disease, as well as the patient's age and general health, will determine which treatment should be utilized. Additionally, these modalities can be combined if indicated. Indeed, the multimodality approach appears to provide the most positive results for treating mesothelioma.
Surgery, the most common treatment, involves the removal of the tumor. In the early stages of mesothelioma, this only involves removal of a section of the mesothelium and surrounding tissue, but may require removing part of the diaphragm as well. For more advanced stages of the disease, removing the entire lung may be the only option, which is known as pneumonectomy.
Radiation therapy, also known as radiotherapy, destroys and shrinks the cancer cells through various types of radiation. Both external (such as a machine) and internal (such as radioisotopes) radiation therapies can be utilized effectively to treat malignant mesothelioma.
Finally, chemotherapy, a systemic treatment modality, uses anticancer drugs to destroy the cancerous cells throughout the body. The majority of drugs used to treat mesothelioma are delivered intravenously. The effectiveness of intracavitary chemotherapy, the process of directly injecting the drugs into the chest or abdominal cavity, is being studied.
Pain and other symptoms caused by fluid build-up around the chest and/or abdomen can be treated by drain excess fluid through a needle or tube. These procedures are known as thoracentesis (chest) and paracentesis (abdomen). Drugs, radiotherapy, and surgery can also relieve or prevent further fluid accumulation.
Physicians are currently studying other treatment modalities, such as immunotherapy, gene therapy, and intraoperative photodynamic therapy.
Due to the poor prognosis associated with mesothelioma, regardless of proper treatment, in many cases palliative care is the preferred, and only, option available to patients. This is particularly true for the advanced stages of the disease. By treating the symptoms rather than the disease itself, the goal of this approach is to obtain "quality" of life instead of "quantity" of life. Palliative care aims to relieve the patient s discomfort caused by dyspnea and pain. Chemotherapy, radiation, and/or surgical pleurodeis, in combination with effective management of pain and respiratory function should form the basis of proper palliative care of mesothelioma. Techniques to reduce stress, such as acupuncture, aromatherapy, massage, and reflexology, can provide addition benefit to the patient's sense of well-being.
The stage and location, what cell-type is involved, as well as the patient's age and histology factor greatly on life expectancy. Unfortunately, even with aggressive treatment, the prognosis for mesothelioma patients is poor. Pleural mesothelioma offers a median survival time of approximately 16 to 17 months after initial symptoms. Prognosis for peritoneal mesothelioma is poorer and has a median survival time of only ten months after initial symptoms. Unfortunately, the more advanced stages of mesothelioma may offer as little as four or five month's survival time.
The survival time for patients with localized mesothelioma can be extended several months with aggressive therapy, with roughly 20% of patients surviving past the five-year mark. Therapy programs recently developed at leading cancer centers have extended this survival time even further. Dr. Sugarbaker, of the Brigham and Women's Center in Boston, has achieved a median of 40% survival rate at five years with his treatment regimen for pleural mesothelioma, as reported in the Journal of Thoracic and Cardiovascular Surgery. Other programs are also exhibiting favorable results. However, despite such successes, no cure for mesothelioma currently exists.
Asbestos — A naturally occurring mineral, utilized worldwide for its durability and heat resistant qualities. Extremely fibrous in nature, asbestos particles can easily enter the respiratory system and damage sensitive tissue. This damage can result in asbestosis, mesothelioma, and lung cancer.
Dyspnea — A difficulty in breathing or shortness of breath, typically associated with some form of heart or lung disease. Also known as air hunger.
Mesothelium — A membrane/sac that that protects the body's major internal organs and allows them freedom of movement (for example, lung contractions). The mesothelium is comprised of several regions, including the abdominal cavity (peritoneum), the chest cavity (pleura), and pericardium (heart).
Pleural effusion — An abnormal accumulation of fluid in the pleura, a fibrous membrane that lines the inside of the chest cavity and protects the lungs. This accumulation can cause shortness of breath, cough, and chest pain.
Avoiding or limiting exposure to asbestos is the best way to prevent mesothelioma. Unfortunately, because of the significant delay between exposure and onset (30 to 40 years), it is probably too late to prevent the development of mesothelioma for most patients. Not smoking may slow the disease's progression and/ or prevent other further complications associated with asbestos exposure.
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Sugarbaker, David, et al. "Resection Margins, Extrapleural Nodal Status, and Cell Type Determine Postoperative Long-Term Survival in Trimodality Therapy of Malignant Pleural Mesothelioma." Journal of Thoracic and Cardiovascular Surgery 117 (January, 1999): 54-65
van Ruth, Serge, Paul Baas, and Frans Zoetmulder. "Surgical Treatment of Malignant Pleural Mesothelioma." Chest 123 (February, 2003): 551-561
Mesothelioma Research Foundation of America. 5716 Corsa Ave., Suite 203, Westlake Village, CA 91362. (800) 281-9804. 〈http://www.mesothelioma-rfa.org〉.
The Mesothelioma Center. 1030 Fifth Ave., Pittsburgh, PA 15219. (412) 471-3980. http://mesotheliomacenter.org.
"Malignant Mesothelioma." National Cancer Institute http://www.nci.nih.gov/cancertopics/types/malignantmesothelioma/.
"Mesothelioma." Mesothelioma Information http://www.mesoinfo.com.
"Mesothelioma." Mesothelioma Web http://www.mesotheliomaweb.org.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
a malignant tumor made up of cells derived from the mesothelium.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
A rare neoplasm derived from the lining cells of the pleura or peritoneum that grows as a thick sheet covering the viscera and is composed of spindle cells or fibrous tissue that may enclose glandlike spaces lined by cuboidal cells.
[mesothelium + G. -oma, tumor]
Farlex Partner Medical Dictionary © Farlex 2012
mesothelioma(mĕz′ə-thē′lē-ō′mə, mĕs′-, mē′zə-, -sə-)
n. pl. mesothelio·mata (-mə-tə) or mesothelio·mas
A usually malignant tumor of mesothelial tissue, especially that of the pleura or peritoneum.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
mesotheliomaA neoplasm of serosal surfaces (pleura, peritoneum, pericardium, tunica vaginalis, scrotum) seen in 5–10% of those occupationally exposed to asbestos—especially crocidolite and amosite fibres—with a latency period of 20–40 years. The incidence of mesothelioma increases exponentially if the patient is also a smoker.
Up to 10% of workers heavily exposed to asbestos die from mesothelioma.
Butchart staging of pleural mesothelioma
I—Tumour confined to ipsilateral pleura and lung.
II—Tumour involving contralateral pleura, chest wall, mediastinum, pericardium.
III—Tumour involving both the thorax and abdomen or extrathoracic lymph nodes.
IV—Distant blood-borne metastases.
Proposed TNM staging
• T1—Limited to ipsilateral pleura only;
• T2—Superficial local invasion;
• T3—Deep local invasion;
• T4—Extensive direct invasion.
• N0—No positive lymph node;
• N1—Positive ipsilateral hilar LN;
• N2—Positive mediastinal LN;
• N3—Positive contralateral hilar LN.
• M0—No metastases;
• Ml—Blood-borne or lymphatic metastases.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
mesotheliomaSurgery A neoplasm of serosal surfaces–pleura, peritoneum, pericardium, tunica vaginalis, scrotum, seen in 5-10% of those occupationally exposed to asbestos, with a latency period of 20-40 yrs; incidence of mesothelioma ↑ exponentially if the subject is also a smoker; up to 10% of heavily asbestos-exposed workers die of mesothelioma. See Asbestos, Cystic mesothelioma.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
A rare malignant neoplasm, derived from the lining cells of the pleura and peritoneum, which grows as a thick sheet covering the viscera.
[mesothelium + G. -oma, tumor]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
mesotheliomaA slow-growing benign or malignant tumour of MESOTHELIUM. Malignant pleural mesothelioma is almost entirely the result of exposure to asbestos dust 25 to 50 years previously. Loss of tumour suppressor genes is a feature of the lesion. In Britain today there are about 1800 deaths per year from this cause and these are expected to peak between 2011 and 2015. Mesothelioma can also occur in the abdomen and in the tunica vaginalis of the testis. Radical surgery has been advocated for malignant pleural mesothelioma. Suggestions that SV40 may have an aetiological link have been challenged.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
Patient discussion about mesothelioma
Q. Why have i been seeing so many commercials regarding asbestos related mesothelioma? I have been quite curious to know why law firms are pushing mesothelioma ads.
A. Most people who develop mesothelioma have worked on jobs where they inhaled asbestos particles.The liability resulting from the sheer number of lawsuits and people affected has reached billions of dollars.The amounts and method of allocating compensation have been the source of many court cases, reaching up to the United States Supreme Court.More discussions about mesothelioma
so where ever there's money- there's lawyers..
so where ever there's money- there's lawyers..
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