Colorectal adenomas. Distribution, incidence of malignant transformation, and rate of recurrence.

In 282 patients, 731 colon polyps (643 adenomas and 88 hyperplastic polyps) were extirpated endoscopically or biopsied and investigated histologically. Localization of the adenomas with various degrees of atypia and the hyperplastic polyps, as well as their size distribution, were determined. In 66 patients with adenoma polypectomy on the first examination, one or more control colonoscopies were carried out (in all, 107). The median period of follow-up observation was 31 months. Thirty percent of the one-year control colonoscopies after polypectomy revealed new adenomas. The statistical analyses showed that patients with singular adenomas, on initial investigation, develop significantly fewer adenomas in the further course than patients with multiple initial findings, especially in negative results in the one-year control. The size of new adenomas found during the first 24 months after polypectomy does not exceed 10 mm. On the basis of these results and the literature data available so far, a follow-up program is presented for discussion.