Summary: Oral Contraceptives and Breast Cancer

Women who have ever used early formulations of oral contraceptives and who also have a first-degree relative with breast cancer may be at a particularly high risk for breast cancer.

• According to the Journal of the American Medical Association (JAMA), a recent study was conducted to determine whether the association between oral contraceptive use and the risk of breast cancer is influenced by family history of the disease. An earlier study had been conducted between 1944 and 1952 on 426 women and their families who had been diagnosed with breast cancer. This more current study focused on the sisters, daughters, granddaughters, nieces, and daughters-in-law of the women who had been the focus of the first study. After accounting for each woman’s age and birth cohort, the study showed that using oral contraceptives had significantly increased the risk of breast cancer among the sisters and the daughters. However, the granddaughters, nieces, and daughters-in-law were not found to have as high of a risk of getting the disease. Factors such as age at first birth, age of menarche, age at menopause, smoking, etc. were taken into account although the results were essentially unchanged by these factors. The elevated risk among women with a first-degree family history of breast cancer was most evident for oral contraceptive use during or prior to 1975, when the medications were likely to contain higher dosages of estrogen and progestins. The researchers of this study concluded that the results suggest that women who have ever used earlier formulations of oral contraceptives and who also have a first-degree relative with breast cancer may be at particularly high risk for breast cancer. However, further studies of women with a strong family history who have used more recent lower-dosage formulations of oral contraceptives are needed to determine how women with a familial predisposition to breast cancer should be advised regarding oral contraceptive use today.¹

¹Oral Contraceptives and Breast Cancer: A Note of Caution for High-Risk Women, The Journal of the American Medical Association, Vol. 284, No. 14, October 11, 2000, pp. 1-6.