Risk of Incident Cancer in Patients With Inflammatory Bowel Disease With Prior Breast Cancer: A Multicenter Cohort...

Breast cancer is the most common malignancy observed in patients with inflammatory bowel diseases (IBD). The aim of our study was to evaluate incident cancer rate (recurrence or new-onset cancer) in a cohort of patients with IBD with a history of breast cancer according to the subsequent IBD treatment provided.

A multicenter retrospective study included consecutive patients with IBD with prior breast cancer. The inclusion date corresponded to the diagnosis of index malignancy. Follow-up lasted from cancer diagnosis until the occurrence of incident cancer.

Among 207 patients included (median disease duration, 13 years [interquartile range, 6-21]), first-line treatment (median interval of 28 months [interquartile range, 7-64]) was a conventional immunosuppressant in 19.3% of patients, anti-tumor necrosis factor in 19.8%, vedolizumab in 7.2%, and ustekinumab in 1.9%. After a median follow-up of 71 months (interquartile range, 34-148), 42 (20%) incident cancers were observed (34 breast cancer recurrences). Adjusted incidence rates per 1000 person-years were 10.2 (95% confidence interval, 6.0-16.4) for the untreated arm and 28.9 (95% confidence interval, 11.6-59.6) for exposed patients (P = .0519). There was no significant difference between treated patients and control subjects regarding incident cancer-free survival rates (P = .4796). In multivariable analysis, factors associated with incident cancer were stage T4d (P = .036), triple negative tumor (P = .016), and follow-up of less than 71 months (P = .005).

We did not find a statistically significant increase in incident breast cancer related to IBD treatment beyond the already known poor prognostic factors of breast cancer.