An epidemiologic study of fibrocystic breast disease with reference to ductal epithelial atypia.

A case-control study of 255 women with fibrocystic breast lesions and 790 controls was conducted at two hospitals in New Haven, Connecticut during 1977-1979. Cases were found to weigh significantly less than controls, and were more likely than controls to have: a first-degree female relative with a history of breast cancer; a higher level of education; a recent history of regular gynecologic checkups; and (if under age 45 years) a later age at first pregnancy. They were less likely to have had a surgical menopause. The degree of ductal epithelial atypia in breast biopsy specimens was evaluated in order to see whether epidemiologic characteristics differed according to the degree of ductal atypia. The only variable to show a linear relationship with ductal atypia was a recent history of regular gynecologic checkups; those with no or minimal atypia were more likely to have had recent checkups than those with high atypia scores. This study thus gives no evidence that known risk factors for breast cancer are more strongly associated with fibrocystic breast disease with a high degree of atypia than with fibrocystic breast disease with a low degree of atypia. It also provides data to support the belief that women having frequent gynecologic checkups are more likely to be included as cases in case-control studies of fibrocystic breast disease, and particularly in the groups with no or minimal atypia, than those not having frequent checkups.