Breast and Prostate Cancer: All in the Family?

Family history of breast cancer or prostate cancer is a well-known risk factor for these diseases. But whether family history of both cancers compounds that risk is unclear. Investigators studied 78,171 participants (age range, 50–79) in the Women's Health Initiative Observational Study. Of these women, 3506 (4.5%) had breast cancer diagnoses during a median of 132 months of follow-up.

Having a first-degree relative with either breast cancer or prostate cancer was associated with excess risk for breast cancer (adjusted hazard ratio, 1.42 and 1.14, respectively), whereas a family history of both cancers among first-degree relatives was associated with higher risk (aHR, 1.78). Breast cancer risk was higher for black women with first-degree fam…