No link between IBD treatment and breast cancer

Medications used to treat inflammatory bowel disease (IBD) do not contribute to an increase in the risk of breast cancer, according to a retrospective study.

The study included 207 patients (97.6 percent female) with IBD and breast cancer. Of the patients, 60.8 percent had Crohn’s disease, 37.7 percent had ulcerative colitis, and 1.5 percent had unclassified IBD. The median age at IBD diagnosis was 38 years. IBD was diagnosed after the breast cancer index diagnosis in 18.4 percent of the patients. In the others, the median IBD duration at index breast cancer diagnosis was 167 months.

In terms of IBD medication, most patients (51 percent) had been exposed to conventional immunosuppressants, 43 percent to anti-TNF, 6 percent to vedolizumab, and 3.6 percent to ustekinumab. The medication used in the first-line setting was a conventional immunosuppressant in 19.3 percent of patients, an anti-TNF in 19.8 percent, vedolizumab in 7.2 percent, and ustekinumab in 1.9 percent.

Over a median follow-up of 71 months, 42 cases of breast cancers were documented, including 34 cases of recurrence. Adjusted incidence rates of breast cancer were 10.2 per 1,000 person-years (95 percent confidence interval [CI], 6.0–16.4) in the IBD treatment-exposed arm and 28.9 per 1,000 person-years (95 percent CI, 11.6–59.6) in the unexposed arm (p=0.0519). Incident cancer-free survival rates did not significantly differ between the two arms (p=0.4796).

These findings may help clinicians make decisions to start immunosuppressants or biologics in case of IBD flare-up in this population.