Risk of Breast Cancer Associated With Reproductive and Fertility Factors According to a Family History of Breast Cancer

摘要

Several reproductive factors have been consistently associated with increased risk of breast cancer in the general population. These associations are less well characterized in women with a family history of the disease. The purpose of this research was to examine the association of reproductive factors with breast cancer risk among sisters, daughters, granddaughters, and nieces of 426 breast cancer probands as well as among women who married into the 426 families. The risk of breast cancer associated with age at menarche, age at menopause, parity, age at first birth, age at last birth, and infertility was not significantly modified by family history. However, our results suggest that use of early formulations of oral contraceptives by women with a strong family history may further elevate their breast cancer risk. The association was particularly strong in families with multiple cases of breast and ovarian cancer. We were not able to draw conclusions regarding use of more recent low dose oral contraceptives. Women in high-risk families have been counseled to take oral contraceptives to reduce their risk of ovarian cancer. Further research is needed to ensure this does not come at the cost of an increased risk of breast cancer.