Endoscopic polypectomy. Therapeutic and clinicopathologic aspects.

The problem of the malignant potential of neoplastic colonic polyps is being, in large measure, resolved by newly derived techniques. Now most polyps may be removed endoscopically using the fiberoptic colonoscope. The largest world experience is at the Beth Israel Medical Center in New York, where over 2000 polyps have been endoscopically removed without a single death and with but one complication requiring operative intervention. Laparotomy is now reserved for polyps not suitable for endoscopic resection or where a question of residual cancer exists. Experience with endoscopic resection has called for: 1) re-assessment of colonic polyps in terms of their malignant potential; and 2) clarification of the indications for laparotomy and bowel resection subsequent to or instead of endoscopic removal. Among all polypoid lesions 0.5 cm or greater in size in the Beth Israel series, a variety of pathologic types was encountered. If only the neoplastic polyps were considered, the incidence of "malignant change" was 10.5% for 855 polyps analyzed. There is, however, a need to clarify terminology and to differentiate between carcinoma in situ and invasive cancer whenever possible. Superficial cancers (carcinomas in situ) do not recur or metastasize and require no treatment other than polyp removal. When "invasive" cancer is present (4.5% of neoplastic polyps) or the lesion is a "polypoid carcinoma" each case must be individually evaluted. Criteria for diagnosis, gross morphological features suggesting cancerous change, and current management of "malignant" polyps are discussed. Colonoscopy is an important component of the followup program whether malignant polyps are resected endoscopically or by the transabdominal route.