Colonic adenomas--a colonoscopy survey.

A colonoscopy survey of 620 patients with 1049 colon adenomas showed a predominantly left-sided distribution (77%). Of these lesions 97% were amenable to endoscopic removal or ablation. Sixty per cent of patients presented with rectal bleeding as their major symptom. There was agreement between radiology and colonoscopy in only 62% of patients, as many of the studies were single contrast barium enemas, performed before referral. Forty-eight per cent of adenomas in our series were less than 1.0 cm in diameter. Of the larger adenomas (greater than 2.0 cm in diameter) 66% were situated in the sigmoid colon, and of those containing invasive carcinoma (4.8% of the total) an even higher percentage (94%) were in the sigmoid and low descending colon. With increasing polyp size, there was a greater predominance of villous elements and this was associated with a higher risk of malignant change than the more frequent and generally smaller tubular adenoma. Local colonoscopic excision alone is sufficient treatment for adenomas with malignant change unless they are poorly differentiated histologically and providing adequate resection is demonstrated. Twenty-eight patients treated in this way are alive without recurrence at periods from six to 62 months. Although 65% of patients had only one adenoma, and 90% three or less, there is a risk of developing other benign and malignant colon neoplasms and careful follow-up is required.