在乳腺癌风险预测中增强乳腺X线密度测量
Enhancement of mammographic density measures in breast cancer risk prediction.
作者信息
Cheddad Abbas, Czene Kamila, Shepherd John A, Li Jingmei, Hall Per, Humphreys Keith
机构信息
Authors' Affiliations: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden;
Department of Radiology and Biomedical Imaging, UCSF School of Medicine, University of California, San Francisco, California; and.
出版信息
Cancer Epidemiol Biomarkers Prev. 2014 Jul;23(7):1314-23. doi: 10.1158/1055-9965.EPI-13-1240. Epub 2014 Apr 10.
BACKGROUND
Mammographic density is a strong risk factor for breast cancer.
METHODS
We present a novel approach to enhance area density measures that takes advantage of the relative density of the pectoral muscle that appears in lateral mammographic views. We hypothesized that the grey scale of film mammograms is normalized to volume breast density but not pectoral density and thus pectoral density becomes an independent marker of volumetric density.
RESULTS
From analysis of data from a Swedish case-control study (1,286 breast cancer cases and 1,391 control subjects, ages 50-75 years), we found that the mean intensity of the pectoral muscle (MIP) was highly associated with breast cancer risk [per SD: OR = 0.82; 95% confidence interval (CI), 0.75-0.88; P = 6 × 10(-7)] after adjusting for a validated computer-assisted measure of percent density (PD), Cumulus. The area under curve (AUC) changed from 0.600 to 0.618 due to using PD with the pectoral muscle as reference instead of a standard area-based PD measure. We showed that MIP is associated with a genetic variant known to be associated with mammographic density and breast cancer risk, rs10995190, in a subset of women with genetic data. We further replicated the association between MIP and rs10995190 in an additional cohort of 2,655 breast cancer cases (combined P = 0.0002).
CONCLUSIONS
MIP is a marker of volumetric density that can be used to complement area PD in mammographic density studies and breast cancer risk assessment.
IMPACT
Inclusion of MIP in risk models should be considered for studies using area PD from analog films.
背景
乳腺X线密度是乳腺癌的一个重要风险因素。
方法
我们提出了一种新的方法来增强面积密度测量，该方法利用了乳腺外侧位X线片中出现的胸肌相对密度。我们假设乳腺胶片的灰度被归一化为乳房体积密度，而不是胸肌密度，因此胸肌密度成为体积密度的一个独立标记。
结果
通过对瑞典一项病例对照研究（1286例乳腺癌病例和1391例对照对象，年龄50 - 75岁）的数据进行分析，我们发现，在调整了经过验证的计算机辅助密度百分比（PD）测量值Cumulus后，胸肌的平均强度（MIP）与乳腺癌风险高度相关[每标准差：比值比（OR）= 0.82；95%置信区间（CI），0.75 - 0.88；P = 6×10⁻⁷]。由于使用以胸肌为参考的PD而非基于标准面积的PD测量值，曲线下面积（AUC）从0.600变为0.618。我们表明，在有基因数据的一部分女性中，MIP与一个已知与乳腺X线密度和乳腺癌风险相关的基因变体rs10995190相关。我们在另外一组2655例乳腺癌病例中进一步重复了MIP与rs10995190之间的关联（合并P = 0.0002）。
结论
MIP是体积密度的一个标记，可用于在乳腺X线密度研究和乳腺癌风险评估中补充面积PD。
影响
对于使用模拟胶片的面积PD的研究，应考虑将MIP纳入风险模型。
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