Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA.
J Natl Cancer Inst. 2011 Feb 2;103(3):273-8. doi: 10.1093/jnci/djq500. Epub 2010 Dec 16.
Body mass index is inversely associated with risk of premenopausal breast cancer, but the underlying mechanisms for this association are poorly understood. Abdominal adiposity is associated with metabolic and hormonal changes, many of which have been associated with the risk of premenopausal breast cancer. We investigated the association between body fat distribution, assessed in 1993 by self-reported waist circumference, hip circumference, and waist to hip ratio, and the incidence of premenopausal breast cancer in the Nurses' Health Study II. Cox proportional hazards regression models were used to calculate hazard ratios and 95% confidence intervals (CIs). Statistical tests were two-sided. During 426,164 person-years of follow-up from 1993 to 2005, 620 cases of breast cancer were diagnosed among 45,799 women. Hormone receptor status information was available for 84% of the breast cancers. The age-standardized incidence rates of breast cancer were 131 per 100,000 person-years among those in the lowest quintile of waist circumference and 136 per 100,000 person-years among those in the highest quintile. No statistically significant associations were found between waist circumference, hip circumference, or the waist to hip ratio and risk of breast cancer. However, each of the three body fat distribution measures was statistically significantly associated with greater incidence of estrogen receptor (ER)-negative breast cancer. The multivariable-adjusted hazard ratios of ER-negative breast cancer for the highest vs the lowest quintile of each body fat distribution measure were 2.75 (95% CI = 1.15 to 6.54; P(trend) = .05) for waist circumference, 2.40 (95% CI = 0.95 to 6.08; P(trend) = .26) for hip circumference, and 1.95 (95% CI = 1.10 to 3.46; P(trend) = .01) for waist to hip ratio. Our findings suggest that body fat distribution does not play an important role in the overall incidence of premenopausal breast cancer but is associated with an increased risk for ER-negative breast cancer.
体重指数与绝经前乳腺癌的风险呈负相关，但这种关联的潜在机制尚不清楚。腹部肥胖与代谢和激素变化有关，其中许多与绝经前乳腺癌的风险有关。我们研究了 1993 年通过自我报告的腰围、臀围和腰臀比评估的体脂分布与护士健康研究 II 中绝经前乳腺癌发病之间的关系。使用 Cox 比例风险回归模型计算风险比和 95%置信区间（CI）。统计检验为双侧。在 1993 年至 2005 年期间进行的 426,164 人年随访中，在 45,799 名女性中诊断出 620 例乳腺癌。84%的乳腺癌可获得激素受体状态信息。腰围最低五分位的乳腺癌年龄标准化发病率为 131/100,000 人年，腰围最高五分位的乳腺癌年龄标准化发病率为 136/100,000 人年。腰围、臀围或腰臀比与乳腺癌风险之间未见统计学显著关联。然而，三种体脂分布测量值均与雌激素受体（ER）阴性乳腺癌的更高发病率有统计学显著相关性。每个体脂分布测量值的最高五分位与最低五分位相比，ER 阴性乳腺癌的多变量调整后的风险比分别为 2.75（95%CI=1.15 至 6.54；P（趋势）=0.05），腰围，2.40（95%CI=0.95 至 6.08；P（趋势）=0.26），臀围，1.95（95%CI=1.10 至 3.46；P（趋势）=0.01），腰臀比。我们的研究结果表明，体脂分布在绝经前乳腺癌的总体发病率中不起重要作用，但与 ER 阴性乳腺癌的风险增加有关。
