Risk factors relevant to cystic breast disease: a case-control study.

A total of 188 women aged 40-54 with cystic breast disease and 2213 asymptomatic controls were questioned in Edinburgh between 1974 and 1978 concerning marital, reproductive, and menstrual status, history of oral contraception use, history of previous breast complaints, and a family history of breast cancer. Women with a history of breast biopsy were at an increased risk of the disease and those past the menopause were at a decreased risk. These results agree with previous findings that the disease is most prevalent among premenopausal women and suggest that benign cystic disease of the breast does not share a common aetiology with breast cancer in the age range 40-54.