To Örebro University

BACKGROUND: Cancer incidence data including absolute risk differences are needed for clinical risk communication to patients receiving modern-day treatments for ulcerative colitis (UC).

METHODS: We linked nationwide Swedish health registers and assessed incident cancers in patients with UC in 2007-2022. We computed age-stratified incidence rates (IRs), IR differences and hazard ratios (HRs) in a naïve cohort with no immunomodulatory treatment, and in cohorts treated with thiopurine or targeted therapies. General population comparator subjects were matched (by age, sex, calendar year, and area of residence) to each treatment cohort. We used a once-exposed - always exposed design.

RESULTS: We identified 63,925 patients with UC in partly overlapping cohorts and 593,072 comparators with a total follow-up time of 5,800,089 years (median 8.1 years).The IRs were elevated compared to the general population in naïve patients: 2.7 extra cancer cases per 1000 person years (HR:1.12, 95%CI:1.09-1.16), in thiopurine-treated patients: 3.4 extra cases (HR:1.48;1.37-1.61), TNFi-treated: 2.7 extra cases (HR:1.41;1.24-1.62), Thiopurine+TNFi-treated: 2.42 extra cases (HR:1.44;1.19-1.75), vedolizumab-treated: 2.88 extra cases (HR:1.27;0.90-1.79). The IR differences were not significantly increased in patients treated with ustekinumab 0.57 (HR:0.87;0,39-1.93) and tofacitinib -0.69 (HR:0.84;0.25-2.77). Across all treatment groups, the IR differences compared to the general population were highest in patients ≥60 years. The differences were driven by colorectal cancer, hepatobiliary cancer, lymphoma, and basal cell skin carcinoma.

CONCLUSION: Elevated cancer incidence was observed in patients with UC amounting to around 3 extra cases of cancer per 1000 years. Cancer risks varied more among groups defined by age than by treatment.