Association of body size and fat distribution with risk of breast cancer among Chinese women

Most previous studies addressing the association of body size, weight chang e and body fat distribution with the risk of breast cancer were conducted i n Western societies with a high proportion of overweight people. It remains unclear whether the dose-response relation observed in earlier studies can be extended to women with "normal" weight based on prevailing Western stan dards. To address this issue, we analyzed data from a population-based case -control study of breast cancer recently completed among Chinese women in u rban Shanghai. In-person interviews and anthropometric measurements were co mpleted for 1,459 women newly diagnosed with breast cancer from 25 to 64 ye ars of age and 1,556 controls frequency-matched to cases on age. Unconditio nal logistic regression was employed to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CI) related to anthropometric variables and self-reported body weight. Currently measured weight, body mass index [BMI: weight (kg)/height(m)(2)] or height was each found to be positively relate d to risk of postmenopausal breast cancer in a dose-response manner, with O Rs (95% CI) being 2.0 (1.4-3.0), 2.0 (1.2-3.2) or 1.7 (1.2-2.5), respective ly, for the highest category of weight, BMI or height compared to the lowes t category of these variables. These variables were unrelated to premenopau sal breast cancer risk. Reported weight at ages > 40 years and weight gain after age 20 were more predictive for postmenopausal breast cancer than wei ght at an earlier age. After adjustment for EM I, waist-to-hip ratio was re lated to an increased risk of premenopausal [OR = 1.7 (1.3-2.3) for the hig hest category compared to the lowest category] but not postmenopausal breas t cancer. This study suggests that, even in a relatively thin Chinese popul ation, weight gain and height are related to an increased risk of postmenop ausal breast cancer, while central fat distribution was associated with pre menopausal breast cancer. General weight control may be an effective measur ement for breast cancer prevention. (C) 2001 Wiley-Liss, Inc.