Medical and surgical therapies for patients with inflammatory bowel diseases and prior or coexisting cancer: a Danish nationwide cohort study

Background and aims: As a result of an aging population and the rising incidence of inflammatory bowel diseases (IBD) across all age groups, more patients with IBD are being diagnosed with cancer both before and after their IBD diagnosis. We describe the treatment of patients with IBD with prior or coexisting cancer relative to patients with IBD and no cancer. Methods: Danish national registers were used to identify incident and prevalent patients with IBD, drug exposure, and cancer status, from 1996 to 2022. Cox regressions were used to compare medications and the risk of surgery among patients with and without cancer. Results: In total 59 494 patients with IBD (20 551 Crohn’s disease [CD; 34.5%], 38 943 ulcerative colitis [UC; 65.5%]) were included. Of those, 2675 (4.5%) had been diagnosed with cancer prior to IBD. Of the remaining 56 819 patients with IBD, 6636 (11.7%) had their first cancer develop after their IBD diagnosis. Prior cancer was associated with reduced immunomodulator use for CD and UC, and increased anti-tumor necrosis factor (anti-TNF) use in UC. Furthermore, patients with CD and UC and a history of cancer had an increased risk of undergoing IBD-related surgery during follow-up. Patients who developed cancer during the course of their IBD largely had their anti-TNF and immunomodulator therapy discontinued following a cancer diagnosis. Conclusions: Patients with IBD and prior or coexisting cancer were treated differently from patients with no history of cancer. We observed greater caution around initiating immunosuppressants for patients with prior cancer, while more patients required IBD-related surgery. Greater caution was observed around reinitiating immunosuppressants for patients diagnosed with cancer.