Oral Contraceptives and the Risk of Breast and Ovarian Cancer
Women with BRCA 1/2 mutations who use oral contraceptives (birth control pills) have a significantly reduced risk of ovarian cancer and a non-significantly increased risk of breast cancer, according to the results of a study published in the Journal of Clinical Oncology. This is similar to the risk levels observed in the general population.
Inherited mutations in two genes—BRCA1 and BRCA2—have been found to greatly increase the lifetime risk of developing breast and ovarian cancer. Mutations in these genes can be passed down through either the mother’s or the father’s side of the family.
Researchers conducted a meta-analysis to estimate the risks of ovarian cancer and breast cancer associated with oral contraceptive use among women with an elevated risk of breast and/or ovarian cancer, as a result of family history or mutations in BRCA1/2. The analysis included data from six studies that evaluated ovarian cancer risk and eight studies that evaluated breast cancer risk among women who carry the BRCA1 or BRCA2 mutation.
The results indicated that oral contraceptive use was associated with significantly reduced risk of ovarian cancer among BRCA1 mutation carriers, BRCA2 mutation carriers, and carriers of both. Summary odds ratios for ovarian cancer for ever vs never oral contraceptive users were 0.55 (95% confidence interval [CI] = 0.47–0.66) among BRCA1 mutation carriers, 0.65 (95% CI = 0.34–1.24) among BRCA2 mutation carriers, and 0.58 (95% CI = 0.46–0.73) for carriers of either mutation.
Oral contraceptive use was associated with non-significant increases in risk of breast cancer among among BRCA1 mutation carriers, BRCA2 mutation carriers, and carriers of both. Odds ratios for breast cancer for ever vs never oral contraceptive users were 1.19 (95% CI = 0.92–1.55) among BRCA1 mutation carriers, 1.36 (95% CI = 0.89–2.10) among BRCA2 mutation carriers, and 1.21 (95% CI = 0.93–1.58) among those carrying either mutation.
The researchers noted that women in the general population who have used oral contraceptives (at any point) have a 30 percent reduction in the incidence of ovarian cancer and a small increase in the risk of breast cancer. Current or recent users have a greater risk of breast cancer.
The researchers concluded that their analysis shows that the relationship between oral contraceptive use and ovarian breast cancer among women with BRCA1 or BRCA2 mutations is similar to that of the general population.
Moorman PG, Havrilesky LJ, Gierisch JM, et al. Oral contraceptives and risk of ovarian cancer and breast cancer among high-risk women: A systematic review and meta-analysis. Journal of Clinical Oncology. Published early online October 21, 2013. doi: 10.1200/JCO.2013.48.9021
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