More Right-sided IBD-associated Colorectal Cancer in Patients with Primary Sclerosing Cholangitis

Background: Patients with inflammatory bowel disease (IBD) and concurrent primary sclerosing cholangitis (PSC) have a higher risk of developing colorectal cancer (CRC) than IBD patients without PSC. The aim of this Study was to investigate potential clinical differences between patients with CRC in IBD and those with CRC in IBD and PSC, as this may lead to improved knowledge of underlying pathophysiological mechanisms of CRC development. Methods: The retrospective study from 1980-2006 involved 7 Dutch university medical centers. Clinical data were retrieved from cases identified using the national pathology database (PALGA). Results: In total, 27 IBD-CRC patients with PSC (70% male) and 127 IBD-CRC patients without PSC (59% male) were included. CRC-related mortality was not different between groups (30% versus 19%, P = 0.32); however, Survival for cases with PSC after diagnosing CRC was lower (5-year survival: 40% versus 75% P = 0.001). Right-sided tumors were more prevalent in the PSC group (67% versus 36%, P = 0.006) adjusted for age, sex, and extent of IBD, this difference remained significant (odds ratio: 4.8, 95% confidence interval [CI] 2.0-11.8). In addition, tumors in individuals with PSC were significantly more advanced. Conclusions: The right colon is the predilection site for development of colonic malignancies in patients with PSC and IBD. When such patients are diagnosed with cancer they tend to have more advanced tumors than patients with IBD without concurrent PSC. and the overall prognosis is worse. Furthermore. the higher frequency of right-sided tumors in patients with PSC suggests a different pathogenesis between patients with PSC and IBD and those with IBD alone.