Carcinoma in situ of the distal part of the colon and of the rectum.

One hundred and three patients with carcinoma in situ in the rectum, rectosigmoid and sigmoid colon were evaluated retrospeactively. The majority of the lesions occurred within an adenomatous polyp. A synchronous invasive carcinoma of the colon was present in 43 patients, whereas 42 patients had carcinoma in situ unassociated with another malignant neoplasm or major medical illness. In the latter group of patients, adequate treatment of carcinoma in situ resulted in cure, while two patients who refused treatment died of invasive carcinoma of the colon. Adequate treatment could be obtained by local excision or intestinal resection, depending upon the size and the location of the lesion.