Increased Mortality in Younger Patients with Inflammatory Bowel Disease Associated Colorectal Cancer: A Population-based Cohort Study

Abstract

Background Reported outcomes for colorectal cancer associated with Inflammatory Bowel Disease are inconsistent. We compared survival outcomes in colorectal cancer patients with and without Inflammatory Bowel Disease using a population-based cohort and elicited prognostic factors associated with survival Methods Adult patients with a diagnosis of colorectal cancer in 2007-2015 were identified from the Ontario Cancer Registry. Those with Inflammatory Bowel Disease were detected via the validated Ontario Crohn’s and Colitis Cohort. Primary outcome measure was overall survival from time of colorectal cancer diagnosis until the date of death. Secondary outcome measures included treatments received and publicly-provided health care costs. Results Colorectal cancer was diagnosed in 67,137 with Inflammatory Bowel Disease present in 783 (1.2%). The Inflammatory Bowel Disease-associated colorectal cancer patients were younger at diagnosis (median range 55-59 vs 70-74, p<0.001). Five-year survival in Inflammatory Bowel Disease-associated patients was 56.4% (95% CI 52.6-59.9) and 57.0% (95% CI 56.6-57.4) in sporadic colorectal cancer (p=0.8). Inflammatory Bowel Disease was a significant predictor of death (Hazard Ratio=1.45, 95% CI 1.29-1.63, p<0.001) after adjusting for other variables. In patients under 50, 5-year survival was significantly (p<0.001) reduced in the Inflammatory Bowel Disease population (56.8%, 95% CI 49.4-63.5) compared with the sporadic colorectal cancer population (71.4%, 95% CI 70.0-72.7). Similar results were observed in those 50-64 years old. Conclusion Young patients (<65) with Inflammatory Bowel Disease-associated colorectal cancer have worse survival outcomes than young (<65) patients with sporadic colorectal cancer. These findings inform prognostication and may direct future research for this high-risk population.