The occurrence of severe epithelial dysplasia and its bearing on treatment of longstanding ulcerative colitis.

One hundred twenty-four patients with extensive ulcerative proctocolitis were operated upon with proctocolectomy. The mean observation time was 10.3 years. Before surgery rectal biopsies were taken in all patients. The relationship between precancerous lesion in rectal biopsies and the presence of precancer and/or cancer in the rectum or colon in the removed specimen was evaluated. Thirteen out of 14 patients showed evidence of severe rectal dysplasia as well as severe dysplasia in the large bowel specimen, and five of these patients had a carcinoma as well. The 14th patient showed severe dysplasia only in the rectum as well as a rectal carcinoma. Of 110 patients without severe rectal dysplasia, 36 showed evidence of severe colon dysplasia, and three of these patients had a large bowel carcinoma as well. Only one patient had a large bowel carcinoma without evidence of severe dysplasia in the rectum or colon. Thus, nine patients out of ten with large bowel carcinoma showed severe dysplasia in rectum and/or colon. Four of these carcinomas were unknown before surgery. Although severe dysplasia in the rectal biopsy is a strong indication of a large bowel carcinoma (6/14), a negative rectal biopsy does not exclude a large bowel carcinoma (4/110). Proctocolectomy cannot be looked upon only as a prophylactic procedure in patients with severe dysplasia in the rectal biopsy, but also as an attempt to curative surgery, as large bowel carcinoma may have already developed in a considerable number of patients where precancer is diagnosed in biopsies.