Polyps in the colon. Answers to key questions.

Adenomatous polyps in the adult colon and rectum are of great clinical importance because they can undergo malignant degeneration. Size and histologic type are useful in predicting the likelihood of malignancy. In most cases, biopsy is required to distinguish small adenomas (< 1 cm) from hyperplastic polyps, which do not undergo malignant degeneration. An adenomatous polyp found during proctosigmoidoscopy warrants total colonoscopy with polypectomy, because of the possibility of a synchronous adenoma or cancer. Periodic colonoscopic follow-up is advised, because of the high rate of recurrent ("metachronous") adenomas. The optimal screening technique for colorectal polyps and early cancer in the general population remains to be defined. The most commonly used program at present entails periodic fecal occult blood testing and flexible proctosigmoidoscopy. Diets high in fiber and low in fat may have protective effects against the development of colonic neoplasms.