Department of Community Medicine, School of Medicine, West Virginia University, Mary Babb Randolph Cancer Center, Morgantown, WV 26506, USA.
Am J Epidemiol. 2011 Oct 15;174(8):919-28. doi: 10.1093/aje/kwr192. Epub 2011 Aug 29.
Obesity is a well-established risk factor for postmenopausal breast cancer. Recent studies suggest that smoking increases the risk of breast cancer. However, the effect of co-occurrence of smoking and obesity on breast cancer risk remains unclear. A total of 76,628 women aged 50-79 years enrolled in the Women's Health Initiative Observational Study were followed through August 14, 2009. Cox proportional hazards regression models were used to estimate hazard ratios and 95% confidence intervals. Over an average 10.3 years of follow-up, 3,378 incident cases of invasive breast cancer were identified. The effect of smoking on the risk of developing invasive breast cancer was modified significantly by obesity status among postmenopausal women, regardless of whether the obesity status was defined by body mass index (P(interaction) = 0.01) or waist circumference (P(interaction) = 0.02). A significant association between smoking and breast cancer risk was noted in nonobese women (hazard ratio = 1.25, 95% confidence interval: 1.05, 1.47) but not in obese women (hazard ratio = 0.96, 95% confidence interval: 0.69, 1.34). In conclusion, this study suggests that the effect of smoking exposure on breast cancer risk was modified by obesity among postmenopausal women. The modification effect did not differ by general versus abdominal obesity.
肥胖是绝经后乳腺癌的一个既定危险因素。最近的研究表明，吸烟会增加乳腺癌的风险。然而，吸烟和肥胖同时存在对乳腺癌风险的影响尚不清楚。共有 76628 名年龄在 50-79 岁的妇女参加了妇女健康倡议观察研究，并在 2009 年 8 月 14 日之前进行了随访。采用 Cox 比例风险回归模型估计风险比和 95%置信区间。在平均 10.3 年的随访期间，共发现 3378 例浸润性乳腺癌病例。吸烟对绝经后妇女浸润性乳腺癌风险的影响因肥胖状态而显著改变，无论肥胖状态是通过体重指数（P（交互）=0.01）还是腰围（P（交互）=0.02）来定义。在非肥胖妇女中，吸烟与乳腺癌风险之间存在显著关联（风险比=1.25，95%置信区间：1.05，1.47），但在肥胖妇女中则没有（风险比=0.96，95%置信区间：0.69，1.34）。总之，本研究表明，吸烟暴露对绝经后妇女乳腺癌风险的影响因肥胖而改变。这种修饰效应不因全身肥胖与腹型肥胖而有所不同。
