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Oral Contraceptives and Postmenopausal Hormones Linked to Contralateral Breast Cancer Risk

Strategic Insights

— 1 min read

Recent research from the United States has investigated the association between oral contraceptive (OC) and postmenopausal hormone (PMH) use and the risk of contralateral breast cancer (CBC) in women with a history of breast cancer, particularly those with BRCA1 or BRCA2 deleterious mutations. The WECARE Study, a population-based case-control study of 705 women with asynchronous CBC and 1,398 women with unilateral breast cancer, including 181 BRCA1/2 mutation carriers, found that ever use of OCs was not associated with risk among noncarriers or BRCA2 carriers. However, BRCA1 carriers who used OCs had a nonsignificant greater risk than nonusers. The study also found that total duration of OC use and at least 5 years of use before age 30 were associated with a nonsignificant increased risk among mutation carriers but not among noncarriers.

Key Takeaways:

  • Ever use of OCs was not associated with risk among noncarriers (RR = 0.87; 95% CI = 0.66-1.15) or BRCA2 carriers (RR = 0.82; 95% CI = 0.21-3.13).
  • BRCA1 carriers who used OCs had a nonsignificant greater risk than nonusers (RR = 2.38; 95% CI = 0.72-7.83).
  • Total duration of OC use and at least 5 years of use before age 30 were associated with a nonsignificant increased risk among mutation carriers.
  • Few women had ever used PMH, and no significant associations were found between lifetime use and CBC risk among carriers and noncarriers.
  • The study's authors concluded that the association between OC/PMH use and risk of CBC does not differ significantly between carriers and noncarriers, but a potential small increase in risk may be clinically relevant for carriers with a higher baseline risk of second primaries.

Statistics:

  • 705 women with asynchronous CBC and 1,398 women with unilateral breast cancer participated in the WECARE Study.
  • 181 BRCA1/2 mutation carriers were part of the study.
  • 95% CI for non-BRCA2 carriers using OCs was 0.66-1.15.
  • 95% CI for BRCA1 carriers using OCs was 0.72-7.83.
  • Less than 5% of women had ever used PMH.

Sources:

  • Figueiredo, J. C., et al. "Oral contraceptives and postmenopausal hormones and risk of contralateral breast cancer among BRCA1 and BRCA2 mutation carriers and noncarriers: the WECARE Study." Breast Cancer Research and Treatment 120.1 (2010): 175-183.

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