Benign and malignant breast tumours: epidemiological similarities.

Reproductive risk factors were estimated for 783 cases of cystic disease of the breast, 155 fibroadenoma, 94 miscellaneous breast conditions, and 284 breast cancers. Controls were matched for age, race, ever-married status, time of hospitalization and pay status. The most consistent attributes are a tendency to be still premenopausal, to have had her first pregnancy beyond the age of twenty-five years (or to have had none), and to have had fewer total pregnancies than the control. All are associated with a longer menstrual life prior to onset of the disease than the controls. Findings for cystic disease are compared with other studies. Patients with benign breast disease share some of the demonstrated risk factors for breast cancer.