[Colonic polyps: clinical and practical implications].

Among colorectal polyps, various forms of neoplastic or non-neoplastic lesions are distinguished by histology. Most accumulated knowledge suggests that the majority of cancer of the colon arise in pre-existing benign neoplastic polyps (adenoma-carcinoma sequence). Because of the risk of cancer being already present, all adenomatous polyps must be removed in toto. The carcinoma may occupy only a small area of the polyp, and therefore, forceps biopsies are inappropriate due to the sampling error. Since patients with polyps detected by rectosigmoidoscopy often have further polyps in the remaining part of the colon, complete examination of the whole colon is required. Follow-up examinations are indicated, because the risk of developing new polyps is high. Studies of the life history of the adenoma-carcinoma sequence suggest that interval of complete large-bowel follow-up may be about 5 years. The policy of polypectomy and follow-up examinations should be possible to prevent the development of colorectal cancer.