Hormone Therapy for Cancer Is a Risk Factor for Relapse of Inflammatory Bowel Diseases.

BACKGROUND & AIMS: Exposure to hormone contraception has been associated with an increased risk of relapse of inflammatory bowel diseases (IBDs). Little is known about the effects of cancer therapies, specifically hormone therapies, on the course of IBD. METHODS: We conducted a retrospective cohort study, collecting data from 5 medical centers, on patients with IBD who received a subsequent diagnosis of breast or prostate cancer from 1997 through 2018. For patients with quiescent IBD at their cancer diagnosis, the primary outcome was relapse of IBD. For patients with active IBD at their cancer diagnosis, the primary outcome was IBD remission. RESULTS: Our analysis included 447 patients with IBD (44% with Crohn's disease, 53% with ulcerative colitis, and 3% with IBD unclassified) who had either breast (78%) or prostate (22%) cancer. At their cancer diagnosis, 400 patients (90%) had inactive IBD, and 47 (10%) had active IBD. Among patients with inactive IBD, 112 (28%) developed active IBD. Previous exposure to steroids, immunomodulators, or biologics was associated with IBD relapse after a cancer diagnosis (hazard ratio [HR] for steroids, 1.79; 95% CI, 1.18-2.71; HR for immunomodulators, 2.22; 95% CI, 1.38-3.55; HR for biologics, 1.95; 95% CI, 1.01-5.36). Hormone monotherapy (HR, 2.00; 95% CI, 1.21-3.29) and combination cytotoxic and hormone therapy (HR, 1.86; 95% CI, 1.01-3.43) was associated with IBD relapse. Among 34 patients who received only cytotoxic chemotherapy, 75% remained in remission from IBD at 250 months compared with 42% of those who received hormone monotherapy (log rank, 0.02). Among patients with active IBD at their cancer diagnosis, 14 (30%) entered remission from IBD, but there were no significant factors of achieving IBD remission. CONCLUSIONS: In a multicenter retrospective study, we found that patients with IBD and breast or prostate cancer who receive hormone therapy have an increased risk for relapse of IBD and related adverse outcomes.