Colorectal carcinoma in patients with Crohn's disease.

Epidemiologic studies have shown a fourfold to 20-fold increased risk of colorectal carcinoma in patients with Crohn's disease as compared with the general population, but management for this risk is controversial. This paper presents a series of 10 patients with Crohn's disease and colorectal carcinoma from one institution and a review of the literature. Compared with 118 consecutive patients having colorectal carcinoma of the usual type at the same institution, the 10 patients were younger (mean age 55 vs. 65 yr, p less than 0.05) and had a higher prevalence of mucinous carcinoma (50% vs. 9%, p less than 0.01), providing evidence in addition to the previous epidemiologic results that Crohn's disease is a predisposing (premalignant) condition for colorectal carcinoma. Eight of the 10 patients had an antecedent history of Crohn's disease, ranging from 4 to 51 yr (mean 24 yr); 2 patients presented with colorectal carcinoma and were found to have Crohn's disease. Of particular note, 9 of the 10 patients had colitis or ileocolitis, and carcinoma occurred in bypassed rectum in 2 patients. One patient had two carcinomas. Three of the 11 carcinomas were not recognized preoperatively. The anatomic sites of the cancers were not significantly different from usual colorectal carcinoma, with 7 of the 11 tumors (64%) in the sigmoid colon and rectum. Dysplasia was identified in all 10 patients, and all of the 10 resected carcinomas were found to be contiguous with high-grade dysplasia. The findings in this study support the proposals based upon epidemiologic data that surveillance should be considered for patients with clinically evident colorectal involvement by Crohn's disease or a bypassed segment of colorectum.