A Population-Based Matched Cohort Study of Extra-Digestive Cancer Incidence and Mortality in Individuals With and...

Trends in extra-digestive (ED) cancer incidence and mortality in inflammatory bowel diseases (IBD) may be changing with newer approaches to management.

To study temporal trends and contemporary risks of ED cancers in individuals with and without IBD.

Using population-level administrative data from Ontario, Canada, we studied ED cancer rates among individuals with IBD and age-sex-matched controls (1:10) without IBD between 1994 and 2020. We modelled age-sex-standardised annual cancer incidence (per 100,000 person-years) over time by first-order linear autoregression, and standardised cancer incidence and mortality rate ratios (SIR, SMR) by quasi-Poisson regression.

The average annual percentage change (AAPC) in ED cancer incidence was stable among 110,919 people with IBD (0.108%/year; 95% CI, -0.380, 0.599) but declined among 1,109,190 matched controls (-1.39%/year; 95% CI, -1.57, -1.21). Among those with IBD, AAPC was significant for non-Hodgkin's lymphoma (1.48%/year; 95% CI, 0.161, 2.82), melanoma (1.77%/year; 95% CI, 0.781, 2.77), cervical (2.31%/year; 95% CI, 0.602, 4.10), uterine (4.41%/year; 95% CI, 0.045, 8.96) and thyroid (8.10%/year; 95% CI, 4.31, 12.0) cancers, and statistically greater than controls for cervical, ovarian, lung, and bladder cancers. During 2010-2020, ED cancer incidence was higher in those with IBD (SIR 1.20; 95% CI 1.15, 1.26), while ED cancer-related mortality was specifically higher in those with Crohn's disease (CD; SMR 1.31; 95% CI 1.14, 1.51), as compared to matched controls.

ED cancer incidence has not changed among those with IBD but has declined among matched controls. Beyond 2010, ED cancer incidence is higher among those with IBD and cancer-related mortality is higher among those with CD, relative to matched controls.