Epidemiologic characteristics of benign breast disease.

To see if the risk factors associated with fibroadenoma and cystic disease were similar to those reported for breast cancer, a retrospective study of benign breast tumor in a general population was conducted in Washington County, Maryland. The study population consisted of 320 white women 20 to 49 years of age who had had benign breast disease and 320 age-matched controls. More cystic disease cases than controls had the following characteristics, which had been reported to have been associated with breast cancer in other studies: higher socioeconomic status; fewer pregnancies; and a lack of association with lactation patterns. Nulliparity, late natural menopause and a maternal history of breast cancer were also more common among cystic cases than controls, although these differences could have occurred by chance. Cystic disease cases and controls did not differ with respect to other factors associated with breast cancer, such as early age at menarche, late age at first pregnancy, and negative history of artificial menopause. In contrast to cystic breast disease, fibroadenoma was not associated with most of the risk factors of breast cancer.