Colorectal cancer in inflammatory bowel disease: a continuing problem

Because of the increased risk of colorectal cancer in patients with inflammatory bowel disease, surveillance colonoscopy with mucosal biopsies for dysplasia has been advocated to prevent malignancy or permit its early diagnosis. However, despite adoption of colonoscopic surveillance programs by many clinicians, we have noted a pattern of continued referrals for inflammatory bowel disease-associated malignancy. This study was undertaken in an effort to characterize this cohort of patients.

We reviewed the operative records of a large metropolitan colorectal practice from 1983 to 1995. During this period 40 large-bowel resections were performed for patients with documented inflammatory bowel disease and concomitant carcinoma. A retrospective analysis was conducted with emphasis on clinical presentation, pathologic description, and most recent follow-up.

Mean age at the time of diagnosis of cancer was 48 years with an average inflammatory bowel disease duration of 19 years. Seven patients had documented inflammatory bowel disease for less than eight years before their cancer diagnosis. Carcinomas were identified preoperatively by colonoscopy in 92 percent of patients. One-half of these patients had the colonoscopy to investigate a recent change in inflammatory bowel disease symptoms or signs, whereas the other half underwent endoscopy as routine surveillance. For the remaining 8 percent of patients, operated on for worsening symptoms, the carcinoma was detected in the pathological specimen only. The majority of patients (68 percent) did not have a preoperative diagnosis of dysplasia. Twenty-five percent of tumors were mucinous, 20 percent were multicentric, and 70 percent were located distal to the splenic flexure. Among the seven patients who died, four had pancolitis, six had a recent worsening of symptoms, and all had cancer involving the rectum.

Cancer occurs at a younger age in patients with long-standing inflammatory bowel disease. The tumors are often mucinous, multiple, and located in the left colon. Despite increasing acceptance of surveillance colonoscopy as a recommended strategy in cancer prevention, almost one-half of the patients in this study had their cancer diagnosed because increased colitis symptoms led to colonoscopic examination. Eighteen percent of patients developed cancer with less than an eight-year history of inflammatory bowel disease. These data call into question the effectiveness of dysplasia surveillance as a population-based strategy to decrease the colorectal cancer mortality in inflammatory bowel disease patients.