Family history of breast cancer, age and benign breast disease

A major risk factor for breast cancer is having a first-degree family history of the disease. Benign breast disease (BBD), particularly atypical hyperplasia, is also associated with an increased risk of breast cancer. However, the relationship between family history of breast cancer and BBD is unclear. From 1989 through 1997, 80,995 participants in the Nurses' Health Study II were followed; 16,849 reported a first diagnosis of BBD. Pathology slides were reviewed for 1,465 women who reported having a tissue biopsy, and these were classified as nonproliferative BBD, proliferative BBD without atypia or atypical hyperplasia. Women with a family history of breast cancer were more likely to report a physician diagnosis of BBD [rate ratio (RR) = 1.38, 95% confidence interval (CI) 1.29-1.46]. The magnitude of this association declined with age from RR = 1.96 (95% CI 1.55-2.47) at 25-29 years to RR = 1.20 (95% CI 0.95-1.52) at age 45-50 years. Among women with proliferative disease, those with a family history of breast cancer were almost 3 times as likely to have atypia (prevalence odds ratio = 2.72, 95% CI 1.23-5.89) than those with no family history. In conclusion, women with a family history of breast cancer appear to be at increased risk of being diagnosed with BBD, in particular the high-risk types of BBD associated with a greatly increased risk of breast cancer. This link adds weight to the belief that BBD with atypia is a precursor or marker lesion for breast cancer.