Case-control study of fibrocystic breast disease.

An epidemiological case-control study of FBD has been conducted to evaluate the differences observed between cases and controls in relation to the presence or absence of clinical findings and risk factors for fibrocystic breast disease (FBD). A total of 334 patients with FBD were identified among 6,232 women aged 40-59 who had participated in the National Breast Screening Study in Montréal while 340 age-matched controls were selected at random from the same cohort. All women were interviewed by a well trained nurse. Controls were significantly heavier and had a higher body mass index (BMI) than cases; however, cases had longer school attendance than controls. The menstrual cycle was shorter in cases and the number of pregnancies was greater in controls. Significant odds ratios were observed for BMI (O.R. = 0.72, 95% CI = 0.51 - 1.02) suggesting that a higher value of BMI had a rather protective effect; a similar pattern was observed in women using oral contraceptives. Since nodularity was strongly associated with FBD, it was excluded from a model of logistic regression; in this instance, longer school attendance (> 12 years), older age at menopause (> 45 years) and breast pain were significantly associated with an increased risk of FBD.