Is Hormonal Contraception Associated With Breast Cancer Risk in BRCA-Mutation Carriers?

By: Julia Cipriano, MS
Posted: Friday, November 22, 2024

Based on the results of an observational study of pooled prospective cohort data, which were published in the Journal of Clinical Oncology, hormonal contraception appeared to increase the risk of developing breast cancer for carriers of germline BRCA1—but not BRCA2—mutations. The association was especially pronounced with prolonged use, according to Kelly-Anne Phillips, MD, MBBS, FRACP, FAHMS, of Peter MacCallum Cancer Centre, Melbourne, Australia, and colleagues.

The investigators focused on 3,882 BRCA1- and 1,509 BRCA2-mutation carriers. A total of 53% and 71% of these mutationally defined groups, respectively, had ever used hormonal contraceptives for at least 1 year. Associations between hormonal contraception and breast cancer risk for these unaffected carriers were assessed using Cox regression models. Incident breast cancer was diagnosed in 488 of the individuals with BRCA1 mutations and 191 of those with BRCA2 mutations during a median follow-up of 5.9 and 5.6 years, respectively.

Neither current (hazard ratio [HR] = 1.40, P = .10) nor past (years before, 1–5: HR = 1.16, P = .4; 6–10: HR = 1.40, P = .05; > 10: HR = 1.27, P = .07) use of hormonal contraceptives was found to be significantly associated with breast cancer risk in BRCA1-mutation carriers; however, an association was reported with ever use (HR = 1.29, P = .02). The risk of developing breast cancer was furthermore found to increase with the cumulative duration of use, with an estimated proportional increase of 3% (P = .002) for each additional year. According to the investigators, in BRCA2-mutation carriers, there was no evidence that current (HR = 0.70, P = .3) or ever (HR = 1.07, P = .7) use of hormonal contraception was associated with an increased risk of developing breast cancer.

“Decisions about [the use of hormonal contraceptives] in women with BRCA1 mutations should carefully weigh the risks and benefits for each individual,” the investigators concluded.

Disclosure: For full disclosures of the study authors, visit ascopubs.org.

Journal of Clinical Oncology

---