Background: Ulcerative colitis (UC) patients with primary sclerosing cholangitis (PSC) may have an increased risk for colonic dysplasia or cancer. They also may have higher levels of carcinogenic secondary bile acids and, thus, be more likely to develop cancer in the right side of the colon, where secondary bile acid concentrations are highest.
Methods: Since 1983, 1212 UC patients have undergone total proctocolectomy with ileal pouch-anal anastomosis at the Cleveland Clinic. All 27 patients with PSC were compared with the remaining 1185 patients in a historical cohort study.
Results: Dysplasia detected during cancer surveillance was the indication for surgery in 16 (59.5%) PSC patients and 136 (11.5%) controls [adjusted relative risk (RR), 6.9; 95% confidence interval (CI), 3.0-16.0]. Dysplasia or cancer was found in the resected specimen in 18 (66.7%) PSC patients and 145 (12.2%) controls (RR 10.4, CI 4.1-26.1). Right-sided cancers (proximal to the splenic flexure) were found in all four PSC patients with cancer and in 20 of 49 controls with cancer (RR 2.5, CI 1.3-5.4).
Conclusions: UC patients with PSC are at a significantly increased risk for dysplasia or cancer. The high proportion of right-sided cancers supports the contention that secondary bile acids are carcinogenic and increase the likelihood of cancer in the proximal colon.