Primary sclerosing cholangitis and the risk of colon neoplasia in patients with Crohn’s colitis

Background and aim: Crohn’s colitis (CC) is associated with primary sclerosing cholangitis (PSC). However the risk of colon cancer or dysplasia in CC and PSC is unclear. Our aim was to study the risk of colon neoplasia in CC in patients with and without PSC. Methods: This is a nested, case-control cohort study of all patients diagnosed with concurrent CC and PSC, seen at the Cleveland Clinic between 1985 and 2012. Forty-three patients with both CC and PSC were compared with a random sample of 159 CC controls without PSC during the same period. Results: Seven (16.3%) of 43 CC patients with PSC developed colon cancer or dysplasia, compared with 22 (13.8%) of 159 controls (P = 0.98). Of seven colon neoplasia cases in the PSC group, 100% occurred proximal to the splenic flexure, compared with 50% (11/22) cases of colon neoplasia in controls occurring in the proximal colon (P = 0.001). Based on Cox regression analysis, male gender independently increased the risk of neoplasia [hazard ratio (HR) = 2.68; 95% confidence interval (CI) 1.30–5.54; P = 0.008], as did age at CC diagnosis (HR = 1.29; 95% CI 1.14–1.47; P < 0.001), while the use of azathioprine/6-mercaptopurine was protective (HR = 0.30; 95% CI 0.13–0.70; P = 0.005). The presence of PSC did not increase the risk for colon neoplasia (HR = 0.45; 95% CI 0.18–1.13; P = 0.09). Conclusions: CC patients with PSC appear not to be at increased risk of developing colon neoplasia. Among patients in our cohort with colon neoplasia and concurrent PSC, the neoplasia occurred in the proximal colon in all cases.