PubMed · 7926561
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Y Uno. Polypectomy on multiple polyps.. https://doi.org/10.1016/s0016-5107(94)70239-x
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Colorectal cancer arises from a precursor lesion, the adenomatous polyp, which forms in a field of epithelial cell hyperproliferation and crypt dysplasia. Progression from this precursor lesion to colorectal cancer is a multistep process, accompanied by alterations in several suppressor genes that result in abnormalities of cell regulation, and has a natural history of 10-15 years. Environmental factors and inherited susceptibility play major roles in this sequence of events. As a result of familial and genetic studies, we now have a better understanding of various high-risk groups and the application of screening methods to these individuals and to people at average risk. In the future, further identification of genetically predisposed individuals and colonoscopic screening of the general population may provide new opportunities for control of colorectal cancer through secondary prevention, and a better understanding of lifestyle factors and their modification will lead to improved strategies for primary prevention.
A number of recent publications dealing with colon polyps and cancer emphasize cost-effectiveness and the outcomes of screening and follow-up surveillance of high-risk groups. These groups include patients with either a past personal history or a family history of colorectal adenomas or cancer. Several papers address the effectiveness and compliance with different methods of screening of the asymptomatic, average-risk population for colorectal neoplasia. Other important publications deal with colorectal cancer prevention, the natural history of the adenoma-carcinoma sequence, diagnosis of polyps and cancer, colonoscopic polypectomy, management of the patient with a malignant polyp, and endoscopic treatment of obstructing cancer.
Current practices vary regarding the approach to small polyps discovered during screening flexible sigmoidoscopy. The most common practice is to perform colonoscopy whenever any adenoma is detected, a strategy that generally uses biopsy of polyps < or = 5 mm in size. However, data suggest that tubular adenomas < 1 cm in size in the distal colon have less predictive value than other distal adenomas for advanced adenomas in the proximal colon. Thus, some centers reserve colonoscopy for distal adenomas with tubulovillous or villous histology, > 1 cm in size, or with high-grade dysplasia. At the other end of the spectrum, another school of thought advocates screening colonoscopy, recognizing that most patients with advanced proximal adenomas do not have polyps in their distal colon. Advocates of this approach use any excuse to perform colonoscopy, whether it be a positive fecal occult blood test, minor symptoms, or small polyp at flexible sigmoidoscopy, even if hyperplastic. This review describes the history of the controversy regarding management of findings at flexible sigmoidoscopy, the data pertinent to the controversy, and the basis for the three approaches described above, all of which are currently within the standard of medical care.