Abstract P3-07-04: Effects of statin use on volumetric mammographic density: Results from the Karolinska mammography project for risk prediction of breast cancer (KARMA) study
Authors: Skarping Ida , Brand Judith , Hall Per , Borgquist Signe 
Published: May 2015

Abstract
Introduction:
High mammographic density is an established risk factor for breast cancer, whereas epidemiological data on statins and breast cancer risk have been inconclusive. The aim of this study was to address the role of statins in breast cancer risk by studying their effect on mammographic density in a large screening-based cohort.
Methods:
The KARolinska MAmmography project for the risk prediction of breast cancer (KARMA) study includes 70,876 women who performed either a screening or clinical mammography from January 2011 to December 2013. In all, 41,102 women responded to a web-based questionnaire, and their raw digital mammograms were stored and their volumetric mammographic density was estimated using the Volpara™ system. Information on statin use was obtained through the Swedish National Prescription Register. Analysis of covariance was used to study the effect of current statin use on mammographic density, adjusting for a large set of potential confounders. Analyses were stratified by statin lipophilicity and exposure duration. The potential effect modification by hormone replacement therapy (HRT) was analyzed.
Results:
Statin use was recorded in approximately 3,300 women (8.1%) of the study population of 41,102, the majority of which was prescribed a lipophilic statin (93.4% of statin users). After multivariable adjustment, volumetric percent density was lower in statin users than in non-users (P&lt;0.001). Further, statin users had a larger non-dense volume than non-users (P&lt;0.001), but no difference in absolute dense volume was detected. No differential effects were observed according to lipophilicity of the statin or drug duration. Interaction analyses revealed effect modification by HRT (P-interaction=0.03) with statin use being associated with a larger dense volume among ever HRT users.
Participant characteristicsTotalStatin useP valueNoYesN = 37,765N = 3,337Age (years)55.054.263.8&lt; 0.001BMI (kg/m2)25.425.227.1&lt; 0.001Menopausal status, % (N)&lt; 0.001Premenopausal40.2 (16,506)43.1 (16,272)7.0 (234)Perimenopausal/unknown3.3 (1,349)3.5 (1,304)1.4 (45)Postmenopausal56.6 (23,247)53.5 (20,189)91.6 (3,058)
Volumetric mammographic density measures by current statin use.Model 1Model 2Model 3Model 4Statin useVolumetric percent density (%)No8.017.937.937.94Yes6.897.737.747.66P value&lt; 0.0010.0010.001&lt; 0.001Dense volume (cm3)No56.857.157.157.0Yes60.757.657.558.0P value&lt; 0.0010.310.320.06Statin typeVolumetric percent density (%)None8.017.937.937.94Lipophilic6.927.737.777.69Hydrophilic6.467.327.347.26P value&lt; 0.001&lt; 0.001&lt; 0.001&lt; 0.001Dense volume (cm3)None56.857.157.157.0Lipophilic60.857.757.758.1Hydrophilic58.255.054.855.3P value&lt; 0.0010.200.660.21Model 1: adjusted for age Model 2: Model 1 + BMI Model 3: Model 2 + menopausal status, HRT use, parity, age at menarche, education level, smoking, alcohol consumption and benign breast disease Model 4: Model 3 + low-dose aspirin and metformin use
Conclusions:
Statin use was associated with a lower mammographic percent density, although no evidence was found for an effect of statins on absolute dense volume. The observed interaction between statin and HRT use requires further investigation.
Citation Format: Ida Skarping, Judith Brand, Per Hall, Signe Borgquist. Effects of statin use on volumetric mammographic density: Results from the Karolinska mammography project for risk prediction of breast cancer (KARMA) study [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-07-04.