Abstract

PIP: Age at menopause and type of menopause from hospital records of breast cancer patients were compared with similar information reported by a national probability sample of women. The national sample comprised 3581 women who responded to the 1960-1962 National Health Examination Survey. The cancer series consisted of 3887 patients selected from those reported to the Connecticut Cancer Registry between 1950 and 1959. No substantial bias was identified when the validity of the comparison and the effect of the relatively large number of breast cancer patients whose menopause histories were deficient were evaluated. Overall, surgically induced menopause was associated with a reduction in breast cancer risk to about 60% of that experienced by women having natural menopause induced before age 35, but induction up to age 50 was protective. There was little effect in the 10 years following the surgical procedure, but substantial reduction occurred in all subsequent periods. Among women with menopause induced before age 35, breast cancer risk stayed as low as 1/3 that expected 30 and more years later. Relative risk of breast cancer increased with age at natural menopause. Women with natural menopause at age 55 or older had twice the breast cancer risk experienced by those whose menopause occurred before age 45. The relative risk of breast cancer associated with late natural menopause was greatest after age 70.