Impact of abdominal or pelvic radiotherapy on disease activity in inflammatory bowel disease: a multicentre cohort study from the GETAID.

BACKGROUND: Abdominal or pelvic radiotherapy in inflammatory bowel disease (IBD) patients raises concerns regarding the risk of worsening of underlying disease. AIM: To assess the impact of radiotherapy on IBD course. METHODS: A retrospective multicentre study including IBD patients exposed to abdominal or pelvic irradiation was conducted, retrieving IBD activity by semester (6-month periods) before (from S-4 to S-1) and after (from S + 1 to S + 6) radiotherapy and IBD flare during follow-up. RESULTS: Sixty-one patients (32 women, mean age 59 years), with 467 patient semesters of follow-up, treated for digestive (n = 31), urinary tract (n = 23) and gynaecological cancers (n = 7) were included. Rates of IBD activity per semester were, respectively, 21% (95% CI: 16-27) from S-4 to S-1; 12% (7-19) from S + 1 to S + 3 (P = 0.15 vs S-4 to S-1) and 16% (10-25) from S + 4 to S + 6 (P = 0.45 vs S-4 to S-1). With a median follow-up of 156 weeks (interquartile range: 82-365), rates of survival without IBD flare at 1 and 3 years after radiotherapy were 82.5% (73.2-93.0) and 70.6% (58.8-84.7). Moderate-to-severe acute radiotherapy-induced gut toxicity and the absence of concomitant chemotherapy were independently associated with an increased risk of flare. CONCLUSION: Most patients with non-active IBD can be safely treated with abdominal or pelvic radiotherapy. Patients having acute gut toxicity and those without concomitant chemotherapy should be more closely monitored in the post-radiotherapy period.