Similarity of colorectal cancer in Crohn's disease and ulcerative colitis: implications for carcinogenesis and prevention.

Colorectal cancer is the most frequent malignant complication in patients with inflammatory bowel disease. Eighty patients with colorectal cancer complicating Crohn's disease (CD) or ulcerative colitis (UC) with median ages at diagnosis of colorectal cancer of 54.5 years and 43.0 years respectively were studied. The median duration of disease to the diagnosis of cancer was long (CD 15 years; UC 18 years). Most cancers developed after more than eight years of disease (CD 75%; UC 90%). Patients with multiple carcinomas at diagnosis were equally common (CD 11%; UC 12%). Carcinoma occurred in the area of macroscopic disease in most patients (CD 85%; UC 100%). Mucinous and signet ring histological features were equally common (CD 29%; UC 21%). Dysplasia was present with similar frequency in both diseases (CD 73%; UC 79%). The overall five year survival rates were also similar (CD 46%; UC 50%). These findings show that carcinomas complicating CD and UC have strikingly similar clinicopathological features and suggest that a common underlying process, such as chronic inflammation, maybe important in the pathogenesis of colorectal carcinoma.