Summary: Oral Contraceptives Contribute to Risk of Getting Breast Cancer in Younger Women.

A 2009 study reports that oral contraceptive use contributes to younger women developing breast cancer particularly a type called triple-negative that is aggressive, more difficult to treat and has higher mortality rates.  Among women < 40 years of age, the risk for breast cancer overall, and the risk of non-triple-negative breast cancer increased with younger age at first use. 

Triple-Negative Breast Cancer, an understudied and aggressive type of breast cancer associated with high mortality, occurs more frequently in younger women and in African American women.  This study showed that a strong association exists between oral contraceptive use and the risk for triple-negative breast cancer.  The study was done to assess risk for this type of cancer among women age 45 or younger in relation to demographic/lifestyle factors, reproductive history, land oral contraceptive use.  Known and suspected breast cancer risk factors were examined separately as potential confounders for the main effects of all other risk factors in age-adjusted models.  These were: age (at reference), race, education, annual incomes, family history of breast cancer, body mass index(1 year before reference), smoking history, alcohol consumption, age at menarche, number of live births, age at first birth (still or live), lactation history, abortion history, and oral contraceptive use.  The risk factors of older age, family history of breast cancer, earlier menarche age, induced abortion, and oral contraceptive use were associated with an increased risk for breast cancer.  Oral contraceptive use > 1 year was associated with a 2.5 –fold increased risk for triple-negative breast cancer.  Among oral contraceptive users only, earlier age at first use further elevated the risk of breast cancer.  Risk was decreased in relation to greater number of births and younger age at first birth.  Multivariate-adjusted odds ratios for examined risk factors were consistent with the effects observed in previous studies on younger women.  In women < 40 years of age, oral contraceptive use > 1 year was associated with a > 4-fold increased risk for triple-negative breast cancer and no increased risk for non-triple-negative breast cancer.  Among women < 40 years of age, the risk for breast cancer overall, and the risk of non-triple-negative breast cancer increased with younger age at first use.¹

¹Dolle, Jessica M. and Daling, Janet R. Risk Factors for Triple-Negative Breast Cancer in Women Under the Age 45 Years. Cancer Epidemiology, Biomarkers & Prevention 2009; 18(4) April 2009, pp. 1157-1166.