No Effect of Aspirin on Mammographic Density in a Randomized Controlled Clinical Trial

• Published in: Cancer epidemiology, biomarkers & prevention Vol. 18; no. 5; pp. 1524 - 1530
• Main Authors: MCTIERNAN, Anne, WANG, C. Y, SORENSEN, Bess, LIREN XIAO, BUIST, Diana S. M, AIELLO BOWLES, Erin J, WHITE, Emily, ROSSING, Mary Anne, POTTER, John, URBAN, Nicole
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01-05-2009
• Subjects: Aged; aspirin; Aspirin - administration & dosage; Aspirin - pharmacology; Biological and medical sciences; breast cancer; Breast Neoplasms - diagnostic imaging; Double-Blind Method; Female; Humans; Linear Models; mammographic density; Mammography; Medical sciences; Middle Aged; NSAIDs; Postmenopause; Risk Factors; Tumors; Prostaglandin-endoperoxide synthase; Radiodiagnosis; Enzyme; Enzyme inhibitor; Mammography; Acetylsalicylic acid; Density; Randomized controlled trial; Antiplatelet agent; Non steroidal antiinflammatory agent; Randomization; Analgesic; Cancerology; Antipyretic; Clinical trial; Oxidoreductases; Salicylates
• ISSN: 1055-9965; 1538-7755
• DOI: 10.1158/1055-9965.EPI-08-1088

Background: Epidemiologic studies suggest a reduced risk of breast cancer among women who regularly use aspirin; a plausible
mechanism is through aspirin effect on mammographic breast density, a breast cancer risk factor, possibly mediated through
aspirin interference with estrogen synthesis.
Methods: In a 2-arm randomized placebo-controlled clinical trial, we evaluated the effects of 6-month administration of 325
mg/day aspirin on total mammographic breast dense area and percent of the mammographic breast image occupied by dense areas
(% density) in 143 postmenopausal women. Eligible women, recruited from 2005 to 2007, were healthy, not taking hormone therapy,
with elevated mammographic breast density (American College of Radiology Breast Imaging Reporting and Data System density
category 2, 3, or 4) within 6 months before enrollment.
Results: Women were a mean (SD) 59.5 (5.5) years. Geometric mean baseline percent density was 17.6% (95% confidence interval,
14.8-20.9) in women randomized to aspirin and 19.2% (95% confidence interval, 16.3-22.7) in women randomized to placebo. Percent
density decreased in women randomized to aspirin by an absolute 0.8% versus an absolute decrease of 1.2% in controls ( P = 0.84). Total breast area and dense area decreased to a similar degree in women assigned to aspirin and in those assigned
to placebo, with no statistically significant differences between trial arms.
Conclusions: A single daily administration of adult-dose aspirin for 6 months had no effect on mammographic density in postmenopausal
women. If aspirin affects breast cancer risk in postmenopausal women, it may do so through alternative pathways than mammographic
breast density. (Cancer Epidemiol Biomarkers Prev 2009;18(5):1524–30)