The specific aims of this study were to determine (1) the prevalence of lesions in asymptomatic patients, 45 years of age and over, with negative fecal occult blood tests, by using a 60-cm flexible sigmoidoscope, and to study the histopathology of colorectal lesions in terms of type, size, and location; (2) what proportion of the lesions found were beyond the reach of a 24-cm rigid or a 30-cm flexible sigmoidoscope; (3) what proportion of these patients with significant lesions had additional lesions beyond 60 cm as detected by colonoscopy; and (4) what proportion of these patients with significant lesions would have been referred for colonoscopy if either the 24-cm or the 30-cm sigmoidoscope had been used rather than the 60-cm sigmoidoscope.
Eighty percent of the lesions found by the 60-cm flexible sigmoidoscope were beyond the reach of the rigid sigmoidoscope.
None of these lesions would have been found if, because of a negative fecal occult blood test, the patient had not been examined using a 60-cm flexible sigmoidoscope.
Their earlier research supports the findings of this study; namely, that the 60-cm flexible sigmoidoscope is more effective in detecting lesions than either the shorter rigid or the shorter flexible sigmoidoscope.
It cost the Kaiser HMO an estimated $70 per patient to perform each examination using a 60-cm flexible sigmoidoscope, or $70,000 for the 1000 patients involved in this study.
The relative risk (RR) of colorectal cancer found within reach of the flexible sigmoidoscope is a function of the proportion of distal cancer and the total incidence of cancer for the groups being compared.
This study documents that both race and sex are independent risk factors for colorectal cancer occurring within reach of the flexible sigmoidoscope.
Winawer SJ, Cummings R, Baldwin MP: A new flexible sigmoidoscope for the generalist.