Screening The rationale for colorectal cancer screening programs is that earlier detection of localized, superficial cancers in asymptomatic individuals will increase the surgical cure rate. Such screening programs are important for individuals having a family history of the disease in first-degree relatives. The relative risk for developing colorectal cancer increases to in such individuals and may be even higher if the relative was afflicted before age 60. The prior use of proctosigmoidoscopy as a screening tool was based on the observation that 60% of early lesions are located in the rectosigmoid. For unexplained reasons, however, the proportion of. | Chapter 087. Gastrointestinal Tract Cancer Part 10 Screening The rationale for colorectal cancer screening programs is that earlier detection of localized superficial cancers in asymptomatic individuals will increase the surgical cure rate. Such screening programs are important for individuals having a family history of the disease in first-degree relatives. The relative risk for developing colorectal cancer increases to in such individuals and may be even higher if the relative was afflicted before age 60. The prior use of proctosigmoidoscopy as a screening tool was based on the observation that 60 of early lesions are located in the rectosigmoid. For unexplained reasons however the proportion of large-bowel cancers arising in the rectum has been decreasing during the past several decades with a corresponding increase in the proportion of cancers in the more proximal descending colon. As such the potential for rigid proctosigmoidoscopy to detect a sufficient number of occult neoplasms to make the procedure cost-effective has been questioned. Flexible fiberoptic sigmoidoscopes permit trained operators to visualize the colon for up to 60 cm which enhances the capability for cancer detection. However this technique still leaves the proximal half of the large bowel unscreened. Most programs directed at the early detection of colorectal cancers have focused on digital rectal examinations and fecal occult blood testing. The digital examination should be part of any routine physical evaluation in adults older than age 40 serving as a screening test for prostate cancer in men a component of the pelvic examination in women and an inexpensive maneuver for the detection of masses in the rectum. The development of the Hemoccult test has greatly facilitated the detection of occult fecal blood. Unfortunately even when performed optimally the Hemoccult test has major limitations as a screening technique. About 50 of patients with documented colorectal cancers have a .
