VARIATIONS IN THE RISK OF BREAST-CANCER ASSOCIATED WITH A FAMILY HISTORY OF BREAST-CANCER ACCORDING TO AGE AT ONSET AND REPRODUCTIVE FACTORS

In a case-control study of 495 breast cancer patients and 785 controls between 20 and 56 years of age, the risk of breast cancer associated with a family history of breast cancer was studied according to age an d reproductive factors. The familial risk of breast cancer was not sig nificantly modified by age at onset, age at menarche, number of childr en, age at first full-term pregnancy, menstrual cycle length or age at menopause. However, the familial risk significantly increased with th e number of abortions (p < 0.05) and seemed to decrease after a natura l menopause (p = 0.08). These results suggest that a familial predispo sition to breast cancer exerts the same influence during the first six decades of life, except maybe when there are isolated or repeated eve nts such as abortions or artificially imposed menopause, in which case the risk is apparently greater.