Department of Gynecology and Obstetrics, Erlangen University Hospital, Comprehensive Cancer Center Erlangen/European Metropolitan Area Nuremberg (CCC ER-EMN), Universitätsstrasse 21-23, 91054, Erlangen, Germany.
Institute of Biometry and Epidemiology, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, Germany.
Breast Cancer Res Treat. 2017 Dec;166(3):701-708. doi: 10.1007/s10549-017-4446-7. Epub 2017 Aug 21.
Percentage mammographic density (PMD) is a major risk factor for breast cancer (BC). It is strongly associated with body mass index (BMI) and age, which are themselves risk factors for breast cancer. This analysis investigated the association between the number of full-term pregnancies and PMD in different subgroups relative to age and BMI.
Patients were identified in the breast cancer database of the University Breast Center for Franconia. A total of 2410 patients were identified, for whom information on parity, age, and BMI, and a mammogram from the time of first diagnosis were available for assessing PMD. Linear regression analyses were conducted to investigate the influence on PMD of the number of full-term pregnancies (FTPs), age, BMI, and interaction terms between them.
As in previous studies, age, number of FTPs, and BMI were found to be associated with PMD in the expected direction. However, including the respective interaction terms improved the prediction of PMD even further. Specifically, the association between PMD and the number of FTPs differed in young patients under the age of 45 (mean decrease of 0.37 PMD units per pregnancy) from the association in older age groups (mean decrease between 2.29 and 2.39 PMD units). BMI did not alter the association between PMD and the number of FTPs.
The effect of pregnancies on mammographic density does not appear to become apparent before the age of menopause. The mechanism that drives the effect of pregnancies on mammographic density appears to be counter-regulated by other influences on mammographic density in younger patients.
乳房 X 光摄影密度（PMD）百分比是乳腺癌（BC）的一个主要危险因素。它与体重指数（BMI）和年龄密切相关，而 BMI 和年龄本身也是乳腺癌的危险因素。本分析研究了相对于年龄和 BMI，足月妊娠次数与 PMD 之间的关联在不同亚组中的表现。
在弗兰科尼亚大学乳腺中心的乳腺癌数据库中确定了患者。共确定了 2410 名患者，他们的生育史、年龄和 BMI 信息以及首次诊断时的乳房 X 光片可用于评估 PMD。进行线性回归分析以研究足月妊娠次数（FTPs）、年龄、BMI 及其相互作用项对 PMD 的影响。
与之前的研究一样，年龄、FTPs 数量和 BMI 与 PMD 呈预期方向相关。然而，包括各自的相互作用项进一步提高了 PMD 的预测能力。具体来说，PMD 与 FTPs 数量之间的关联在 45 岁以下的年轻患者中与在年龄较大的组中不同（每次妊娠平均 PMD 单位降低 0.37）。BMI 并没有改变 PMD 与 FTPs 数量之间的关联。
妊娠对乳房 X 光摄影密度的影响似乎在绝经前不会变得明显。驱动妊娠对乳房 X 光摄影密度影响的机制在年轻患者中似乎被其他对乳房 X 光摄影密度的影响所抵消。
