IBD therapies not linked to increased cancer risk among patients with breast cancer history

The risk of new or recurrent cancer related to inflammatory bowel disease (IBD) treatment does not appear to be elevated for IBD patients with a history of breast cancer, according to a large retrospective study.

The study included 207 consecutive IBD patients (median age at diagnosis 38 years, 97.6 percent female, median disease duration 13 years) with prior breast cancer. Of these, 60.8 percent had Crohn’s disease, 37.7 percent had ulcerative colitis, and 1.5 percent had unclassified IBD.

IBD was diagnosed after the breast cancer index diagnosis in 38 patients (18.4 percent). In the others, the median IBD duration at index breast cancer diagnosis was 167 months. First-line treatment used was conventional immunosuppressants in 86 (51 percent) patients, anti-TNF in 73 (43 percent), vedolizumab in 10 (6 percent), and ustekinumab in six (3.6 percent).

Over a median follow-up of 71 months, 42 (20 percent) incident cancers were documented, including 34 breast cancer recurrences. The adjusted incidence rate of cancer was 28.9 (95 percent confidence interval [CI], 11.6–59.6) per 1,000 person-years for IBD treatment-exposed patients vs 10.2 (95 percent CI, 6.0–16.4) per 1,000 person-years for the untreated patients (p=0.0519).

Incident cancer-free survival rates did not differ between the treatment-exposed group and the untreated group (p=0.4796).

In multivariable analysis, the risk factors for incident cancer were stage T4d (p=0.036), triple negative tumour (p=0.016), and follow-up of less than 71 months (p=0.005).

The findings may be useful to clinicians when making decisions regarding initiation of immunosuppressants or biologics in case of IBD flare-up in patients with a history of breast cancer, according to the researchers.