Abstract P2-08-30: Association between skeletal muscle mass and mammographic breast density
Authors: Lee KwanHo , Bang HyeWon , Choi SeungHye 
Published: March 2020

Abstract
Background: Mammographic density (MD) of the breast and body mass index (BMI) are positively associated with the risk of breast cancer in postmenopausal women, but they are inversely associated with each other. We supposed that the reason for this paradox may be due to the heterogeneity of BMI. Therefore, we calculated the skeletal muscle mass index (SMI), and evaluated whether SMI was an independent predictor for MD.
Methods: A cross-sectional study was performed in 143,456 women who underwent comprehensive examinations from 2012 to 2016. Mammographic density was assessed using Breast Imaging Reporting and Data System, and the breasts were classified as dense or non-dense. The association between SMI, anthropometric factors, and MD were estimated using logistic regression models after adjustment for potential confounders.
Results: In all, 115,013 premenopausal women (80.2%) and 28,443 postmenopausal women (19.8%) were included in the analysis. In both pre and postmenopausal women, weight, BMI, SMI and waist circumference were associated with MD. After adjustment for confounding factors including BMI, the odds ratios (ORs) for MD with 95% confidence interval for the dense breasts was between the highest and lowest quartiles of SMI at 2.65 (2.52–2.79) for premenopausal women and at 2.39 (2.02–2.82) for postmenopausal women.
Conclusions: SMI was related to MD independent of BMI, which could be due to the similar growth mechanism of the skeletal muscle and breast parenchymal tissue. The positive correlation between the muscularity and breast density might explain the reason for the paradoxical relationship between BMI, MD and breast cancer risk in previous studies.
Table 1. Characteristics and anthropometric measurements of participants by menopausal status and mammographic densityVariablesAll subjects (n=143 456)Premenopausal womenPostmenopausal womenNon-dense breast (n=60 180)Dense breast (n=54 833)p valueNon-dense breast (n=25 570)Dense breast (n=2873)p valueAge (years)143 45639.3 ± 5.737.3 ± 5.2&lt;0.00158.0 ± 7.550.7 ± 8.2&lt;0.001Height (cm)143 456160.7 ± 5.1161.0 ± 5.0&lt;0.001156.2 ± 5.3158.0 ± 5.2&lt;0.001Weight (kg)143 45658.4 ± 8.853.9 ± 6.9&lt;0.00157.9 ± 8.054.4 ± 7.6&lt;0.001Body mass index (kg/m2)143 45622.6 ± 3.220.8 ± 2.5&lt;0.00123.7 ± 3.121.8 ± 2.9&lt;0.001Age at menarche (years)139 54513.8 ± 1.513.8 ± 1.5&lt;0.00115.4 ± 1.814.8 ± 1.7&lt;0.001Waist circumference143 45677.7 ± 8.273.0 ± 7.0&lt;0.00181.5 ± 8.475.6 ± 8.2&lt;0.001Skeletal mass index143 45637.2 ± 3.139.2 ± 3.0&lt;0.00135.7 ± 3.238.1 ± 3.3&lt;0.001Calcium level adjusted to albumin (mmol/L)140 2788.8 ± 0.38.8 ± 0.3&lt;0.0019.0 ± 0.39.0 ± 0.3&lt;0.001Parous135 92586.680.0&lt;0.00197.793.3&lt;0.001History of estrogen replacement therapy143 4561.11.10.1494.67.0&lt;0.001Data are presented as mean ± standard deviation or %.
Table 2. Multivariate analysis for the association of higher mammographic density with skeletal mass index after further adjustment for BMIPremenopausal womenPostmenopausal womenMultivariate (+BMI) ORa (95% CI)p valueMultivariate (+BMI) ORa (95% CI)p valueSkeletal mass indexQ1 (&lt; 35.5)RefRefQ2 (35.5–37.8)1.26 (1.21 to 1.32)&lt;0.0011.16 (1.01 to 1.33)0.034Q3 (37.8–40.1)1.63 (1.55 to 1.70)&lt;0.0011.55 (1.33 to 1.80)&lt;0.001Q4 (&gt; 40.1)2.65 (2.52 to 2.79)&lt;0.0012.39 (2.02 to 2.82)&lt;0.001aORs and 95% confidence interval (95% CI) from the multivariate model including age, BMI and variables (age at menarche, parous, history of estrogen replacement therapy, calcium level adjusted to albumin.
Citation Format: KwanHo Lee, HyeWon Bang, SeungHye Choi. Association between skeletal muscle mass and mammographic breast density [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-08-30.