Abstract

Background: Inflammatory bowel diseases (IBD) and primary sclerosing cholangitis (PSC) are associated with an elevated risk of colorectal cancer (CRC). While ongoing colonic inflammation is a recognized risk factor for CRC in IBD patients, the impact of concomitant PSC on CRC characteristics and outcomes is not fully understood. This study aimed to compare the clinical features between IBD patients with and without PSC who developed CRC. Methods: We conducted a retrospective study of IBD patients with CRC who had at least 1 colonoscopy at Mayo Clinic within 5 years prior to their CRC diagnosis. These patients were further divided into 2 groups based on the presence of PSC. We collected data on demographics, IBD duration, CRC diagnosis and location, cholangiocarcinoma diagnosis, and liver transplant status. CRC located in the cecum, ascending colon, and transverse colon was classified as right-sided, while CRC in the descending colon, sigmoid colon, and rectum was classified as left-sided. Statistical analyses included Student's t-test for continuous variables and the chi-squared test for categorical data. Results: A total of 119 IBD patients met the inclusion criteria, of whom 50 had concomitant PSC, diagnosed at a mean age of 41 ± 12 years. CRC presented as a single lesion in 96% of cases in both groups. The most common site for CRC was the ascending colon in the IBD-PSC group (32%) and the rectum in the non-PSC group (33%). Right-sided CRCs were more prevalent in the IBD-PSC group (74%) compared to the non-PSC group (50%; p=0.008). Patients in the IBD-PSC group were diagnosed with IBD at a younger age (mean age 32 ± 13 years vs 40 ± 18 years; p=0.01) and also developed CRC earlier (mean age 52 ± 13 years vs 62 ± 16 years; p=0.001) than those in the non-PSC group. Notably, the duration of IBD before CRC diagnosis was not significantly different between the groups. Among the IBD-PSC patients, 44% were diagnosed with CRC after liver transplantation, with an average time gap of 10 ± 7 years. Additionally, 24% of IBD-PSC patients developed concomitant cholangiocarcinoma, whereas no cases were observed in the non-PSC group (P< 0.001). Conclusions: This study demonstrates that IBD patients with concomitant PSC exhibit distinct clinical features compared to those without PSC, including a younger age of onset for both IBD and CRC, and a higher prevalence of right-sided CRCs. The presence of PSC appears to influence the pattern of CRC development, with a significant number of these patients developing CRC after liver transplantation and a notable risk of concomitant cholangiocarcinoma. These findings underscore the need for vigilant CRC surveillance and tailored management strategies in IBD patients with PSC.