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ICARE Newsletter Summer 2014

Is Breast Cancer Risk Affected by Timing of Oral Contraceptives in BRCA1 Carriers?

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Although oral contraceptives (OC) reduce the risk of ovarian cancer in BRCA carriers,1 it is possible that they may raise breast cancer risk. Thus it is important to understand whether age at OC use is a factor when determining impact on breast cancer risk. To address this question, a recent study (which included data from ICARE participants) of ~5000 women with BRCA1 mutations suggested that use of OC before age 25 increases the risk of early-onset breast cancer, and that the risk becomes higher when used for longer periods of time. Two groups were compared (one with breast cancer and one without) to determine whether age at which OC was used impacted breast cancer risk.  Among BRCA1 carriers, breast cancer risk was higher in those who started OC use before age 20 (Odds Ratio (OR): 1.45; 95% CI 1.20; p=0.0001), and also possibly higher in those between ages 20-25 (OR 1.19; 95% CI 0.99-1.42; p=0.06).

Higher breast cancer risk was limited to breast cancer diagnosed before the age of 40. Overall, the authors reported that the risk of early-onset breast cancer increased by 11% with each additional year of OC use when it was started before the age of 20. However, in those diagnosed with breast cancer at or after the age of 40, there was no increased risk of breast cancer based on OC use. These findings suggest that OC use for the purpose of preventing ovarian cancer should be avoided prior to the age of 25.

1.Kotsopoulos J, et al. Breast Cancer Res Treat. 2014 Feb;143(3):579-86. PMID: 24458845.

Permanent link to this article: https://inheritedcancer.net/2nls2014/