University of Hawaii Cancer Center, Cancer Epidemiology Program, Honolulu, HI, USA.
Int J Cancer. 2012 Apr 15;130(8):1915-24. doi: 10.1002/ijc.26205. Epub 2011 Sep 17.
The association of mammographic breast density with breast cancer risk may vary by adiposity. To examine effect modification by body mass index (BMI), the authors standardized mammographic density data from four case-control studies (1994-2002) conducted in California, Hawaii and Minnesota and Gifu, Japan. The 1,699 cases and 2,422 controls included 45% Caucasians, 40% Asians and 9% African-Americans. Using ethnic-specific BMI cut points, 34% were classified as overweight and 19% as obese. A single reader assessed density from mammographic images using a computer-assisted method. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) while adjusting for potential confounders. Modest heterogeneity in the relation between percent density and breast cancer risk across studies was observed (p(heterogeneity) = 0.08). Cases had a greater age-adjusted mean percent density than controls: 31.7% versus 28.5%, respectively (p <0.001). Relative to <20 percent density, the ORs for >35 were similar across BMI groups whereas the OR for 20-35 was slightly higher in overweight (OR = 1.69, 95% CI: 1.28, 2.24) and obese (OR = 1.62, 95% CI: 1.12, 2.33) than in normal weight women (OR = 1.49, 95% CI: 1.11, 2.01). Furthermore, limited evidence of effect modification by BMI of the OR per 10% increase in percent density (p(interaction) = 0.06) was observed, including subgroup analyses by menopausal status and in analyses that excluded women at the extremes of the BMI scale. Our findings indicate little, if any, modification by BMI of the effects of breast density on breast cancer risk.
乳腺密度与乳腺癌风险的关联可能因肥胖程度而异。为了研究体重指数（BMI）的效应修饰作用，作者对 1994 年至 2002 年在加利福尼亚州、夏威夷州和明尼苏达州以及日本岐阜县进行的四项病例对照研究中的乳腺密度数据进行了标准化。1699 例病例和 2422 例对照包括 45%的白种人、40%的亚洲人和 9%的非裔美国人。使用特定种族的 BMI 切点，34%被归类为超重，19%为肥胖。一名读者使用计算机辅助方法从乳腺图像中评估密度。使用逻辑回归来估计比值比（OR）和 95%置信区间（95%CI），同时调整潜在的混杂因素。在研究之间，观察到密度与乳腺癌风险之间的关系存在适度的异质性（异质性检验 p 值=0.08）。病例的年龄调整后平均百分比密度大于对照组：分别为 31.7%和 28.5%（p<0.001）。与<20%的密度相比，>35%的 OR 在 BMI 组之间相似，而超重（OR=1.69，95%CI：1.28，2.24）和肥胖（OR=1.62，95%CI：1.12，2.33）组的 20-35 之间的 OR 略高于正常体重女性（OR=1.49，95%CI：1.11，2.01）。此外，观察到 BMI 对密度每增加 10%的 OR 的效应修饰作用的证据有限（交互作用检验 p 值=0.06），包括按绝经状态的亚组分析和排除 BMI 极端值的女性的分析。我们的研究结果表明，BMI 对乳腺密度与乳腺癌风险之间的关系几乎没有影响。
