Abstract PD1-05: Aspirin use is associated with lower mammographic density in a large screening cohort
Authors: Wood ME , Sprague BL , Oustimov A , Synnstvedt MB , Cuke M , Emily CF , Kontos D 
Published: May 2016

Background: Current breast cancer prevention agents have substantial side effects and do not prevent estrogen receptor negative (ER-) breast cancer. Aspirin is a promising breast cancer prevention therapy; it is cheap, safe, well tolerated, with strong biologic and epidemiologic evidence for a prevention effect on both ER- and ER+ breast cancers. However, clinical trials to date have failed to corroborate a prevention effect; these results are potentially related to study design (dose, duration of therapy and followup, population treated). We sought to evaluate the effect of aspirin on mammographic density, as breast density is a well-accepted, modifiable risk factor for both estrogen receptor positive (ER+) and ER- breast cancer. Methods: Electronic medical records from the University of Pennsylvania were retrospectively evaluated for women from a core set of 36 primary care/ObGyn practices. Individuals were selected if they had both undergone routine screening mammography during 2012-2013 and had an ambulatory visit within the year prior with a confirmed list of medication use. We selected the medication record closest to the screening exam. Logistic regression was performed to test for associations between clinically-recorded BIRADS breast density and aspirin use, after adjusting for the additional risk factors of age, body mass index (BMI) and ethnicity. Results: We identified 26000 women who fit the above criteria, of whom 19.7% reported current aspirin use and 41% were African American. Mean age was 57.3 (standard deviation [sd], 10.9) and mean BMI was 28.9 (sd, 7.3) kg/m2 for the entire cohort. Aspirin users were significantly older and had higher BMI (see Table). There was an independent, inverse association between aspirin use and mammographic density (Ptrend&lt;0.001). Compared to women with extremely dense breasts, women with fatty (OR=1.73, CI: 1.33-2.25) or scattered fibroglandular (OR=1.50; CI: 1.17-1.92) breasts were more likely to be aspirin users. A dose-response pattern was observed, as there was a lower likelihood of having extremely or heterogeneously dense breasts with increasing aspirin dose (OR=0.62, CI: 0.50-0.76 for &gt;300 mg; OR=0.84, CI=0.77-0.91 for &lt;=300 mg; compared to non-users as reference group). The association between aspirin use and density was more pronounced for women &lt;60 and for African American women (p=0.01). Conclusion: We demonstrate an independent association between aspirin use and lower mammographic density in a large, diverse screening cohort. Our results suggest that this association is stronger for younger and African American women: two groups at greater risk for ER- breast cancer. Future evaluation of this cohort will examine duration of aspirin use, and evaluate an automated measure of breast density. These results and others highlight the potential value and need for a randomized, controlled trial of aspirin as a preventive agent for breast cancer.

CharacteristicAspirin Non-UsersAspirin UsersPAge, mean (SD)55.3 (10.2)65.3 (9.8)&lt;0.0001BMI, mean (SD)28.5 (7.2)30.4 (7.6)&lt;0.0001Breast density, no. (%)  OR (95% CI)BIRADS 12006 (9.6)861 (16.9)1.73 (1.33 - 2.25)BIRADS 29346 (44.7)2859 (55.9)1.50 (1.17 - 1.92)BIRADS 38480 (40.6)1312 (25.7)1.22 (0.95 - 1.56)BIRADS 41057 (5.1)79 (1.6)1.00 (Reference)

Citation Format: Wood ME, Sprague BL, Oustimov A, Synnstvedt MB, Cuke M, Emily CF, Kontos D. Aspirin use is associated with lower mammographic density in a large screening cohort. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD1-05.