BODY-SIZE INDEXES AND BREAST-CANCER RISK BEFORE AND AFTER MENOPAUSE

The relationship between various body size indices and breast cancer r isk before and after menopause was elucidated by means of a case-contr ol study conducted between lune 1991 and April 1994 in 6 Italian cente rs on 2,569 patients aged below 75 with histologically confirmed breas t cancer, and on 2,588 controls admitted to the hospital for a wide sp ectrum of acute, non-neoplastic, non-hormone-related diseases. Weight and, more consistently, body mass index (BMI, kg/m(2)) at diagnosis we re inversely related to pre-menopausal breast cancer risk and directly to post-menopausal risk. An 8-unit increase in BMI resulted in an odd s ratio of 0.8 for pre-menopausal and of 1.2 (significant) for post-me nopausal women. Risk seemed to increase gradually after menopause in t he 7th (OR for an 8-unit BMI increase, 1.3) and 8th decades (OR, 1.6) of life. Conversely, height, waist-to-hip ratio, bra cup size and weig ht (or BMI) in adolescence and in young adulthood did not exert a sign ificant or consistent influence on breast cancer risk. The apparent re lationship with BMI at middle age and weight gain between age 30 years and diagnosis was eliminated by allowance for BMI at diagnosis. The a ge-related pattern of the association between BMI and breast cancer ri sk after menopause may reflect a duration-risk relationship, and resem bles the effect of postmenopausal estrogen use, which seems greater am ong older women. (C) 1996 Wiley-Liss, Inc.