Aspirin use is associated with lower mammographic density in a large screening cohort.
Observational and biologic studies suggest that aspirin is a promising prevention therapy for breast cancer. However, clinical trials to date have not corroborated this evidence, potentially due to study design. We evaluated the effect of aspirin on mammographic density (MD), an established modifiable risk factor for breast cancer.



Electronic medical records from the University of Pennsylvania were evaluated for women who underwent screening mammography, saw their primary care provider, and had a confirmed list of medications during 2012-2013. Logistic regression was performed to test for associations between clinically recorded MD and aspirin use, after adjusting for age, body mass index (BMI), and ethnicity.



We identified 26,000 eligible women. Mean age was 57.3, mean BMI was 28.9 kg/m2, 41% were African American, and 19.7% reported current aspirin use. Aspirin users were significantly older and had higher BMI. There was an independent, inverse association between aspirin use and MD (Ptrend< 0.001). Women with extremely dense breasts were less likely to be aspirin users than women with scattered fibroglandular density (OR 0.73; 95% CI 0.57-0.93). This association was stronger for younger women (P = 0.0002) and for African Americans (P = 0.011). The likelihood of having dense breasts decreased with aspirin dose (Ptrend= 0.007), suggesting a dose response.



We demonstrate an independent association between aspirin use and lower MD in a large, diverse screening cohort. This association was stronger for younger and African American women: two groups at greater risk for ER- breast cancer. These results contribute to the importance of investigating aspirin for breast cancer prevention.
Department of Medicine, University of Vermont School of Medicine, Burlington, VT, USA. marie.wood@uvm.edu.
Marie E
ME
Wood
Department of Surgery, University of Vermont School of Medicine, Burlington, VT, USA.
Brian L
BL
Sprague
Department of Radiology, Perelman School of MedicineUniversity of Pennsylvania, Philadelphia, PA, USA.
Andrew
A
Oustimov
Department of Medicine, Perelman School of MedicineUniversity of Pennsylvania, Philadelphia, PA, USA.
Marie B
MB
Synnstvedt
Department of Medicine, University of Vermont School of Medicine, Burlington, VT, USA.
Melissa
M
Cuke
Department of Radiology, Perelman School of MedicineUniversity of Pennsylvania, Philadelphia, PA, USA.
Emily F
EF
Conant
Department of Radiology, Perelman School of MedicineUniversity of Pennsylvania, Philadelphia, PA, USA.
Despina
D
Kontos
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000008:administration & dosage*; D015415:Biomarkers; D000071060:Breast Density / Q000187:drug effects*; D001943:Breast Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D004305:Dose-Response Relationship, Drug; D055088:Early Detection of Cancer; D005006:Ethnicity; D005260:Female; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors
D015415:Biomarkers; D001241:Aspirin
Aspirin; Biomarkers; Breast cancer; Mammographic breast density; Risk