A rationale for the endoscopic management of colonic polyps.

The incidence of invasive cancer in colonic polyps is related to the size of the lesion and the histologic type of the adenoma. It is greatest for villous adenomas and least for tubular adenomas. The malignant potential increases with the size of the polyp, and in lesions 3 cm and larger malignant disease is present in at least 12 per cent. In general, polyps with invasive malignant disease require colon resection, but for pedunculated adenomas, colonoscopic polypectomy is adequate treatment. Even when invasive cancer is close to the line of endoscopic resection but does not invade the stalk or does not display lymphatic or vascular invasion, a case may be made for conservative, endoscopic treatment alone because the occurrence of local or distal metastasis is very unusual.