Abstract P5-08-17: Statin use and mammographic breast density
Authors: Lee Chee Teik , Mi Xiaoyue , Phillip Courtnie R. , Toriola Adetunji T. 
Published: March 2020

Abstract
Background: Mammographic breast density is one of the strongest risk factors for breast cancer. Hence, identifying factors that can reduce mammographic breast density could have utility in breast cancer prevention. A few studies have evaluated the associations of statin use and mammographic breast density, with conflicting results. We, therefore, investigated the associations of statin use with mammographic breast density, and further determined the impact of menopausal status on these associations.
Methods: We evaluated associations in 635 women recruited during annual screening mammogram at the Joanne Knight Breast Health Centre at Siteman Cancer Centre at Washington University School of Medicine, St. Louis, MO, who provided detailed information on many lifestyle factors, including statin use in the past 12 months and had data on mammographic breast density. We evaluated mammographic breast density using Volpara, which provides volumetric measures. Mammographic breast density measures were log10 transformed for conformity to normality. We used linear regression models, adjusted for confounders (age, body mass index (BMI), race, family history of breast cancer, age at first birth and parity, age at menarche and current alcohol intake) to determine the associations between the statin use and mammographic breast density. Least squared means were generated, and back-transformed for easier interpretation.
Results: The mean age of study participants was 52.3 years. Fifty (7.8%) of the 635 women were statin users. The mean BMI among statin users was 31.9kg/m2 vs. 30.5kg/m2 among non-users. After adjusting for confounders, the mean volumetric percent density was lower among statin users (7.6%) than non-users (8.9%), but this was not statistically significant (p-value=0.09). Among premenopausal women, the mean volumetric percent density was 8.3% among statin users vs. 10.3% among non-users (p-value=0.06). Among postmenopausal women, the mean volumetric percent density was 5.2% among statin users vs. 6.4% among non-users (p-value=0.37). On the other hand, non-dense volume was higher among statin users (1519.6 cm3) than non-users (1410.5 cm3; p-value= 0.03).
Conclusion: Statin use was associated with higher non-dense volume but appears to be weakly associated with lower volumetric percent density. The association with volumetric percent density was limited to premenopausal women. Findings require confirmation in other studies.
Table 1 Associations of statin use (in the past 12 months) with volumetric percent density in 635 women attending annual screening mammogram at the Joanne Knight Breast Health Centre, at Siteman Cancer Centre at Washington University School of Medicine, St. Louis, MO.Statin useNumberLeast square meansP-valueP-trendNon-user5858.9ReferenceUser507.60.09Frequency0.07Non-user5858.9Reference1-3 days187.50.544+ days327.60.09
Model adjusted for family history of breast cancer in a first-degree relative (no, yes, and unknown), race (Non-Hispanic White, Black/African American, Others), age at menarche (continuous) current alcohol intake (no, yes), parity (0, 1, 2, ≥3) and age at first birth (continuous).
Frequency: The frequency of statin use, total days per week.
Citation Format: Chee Teik Lee, Xiaoyue Mi, Courtnie R. Phillip, Adetunji T. Toriola. Statin use 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 P5-08-17.