Adolescent caffeine consumption and mammographic breast density in premenopausal women

Purpose: Previous studies suggest that coffee and caffeine intake may be associated with reduced breast cancer risk. To date, there is limited and inconsistent epidemiologic evidence for associations of adolescent diet with mammographic breast density, a strong and consistent predictor of breast cancer. We investigated the association of adolescent caffeine intake with mammographic density in premenopausal women. Methods: This study included 751 cancer-free women within the Nurses’ Health Study II cohort. Percent breast density (PD), absolute dense (DA) and non-dense areas (NDA) were measured from digitized film mammograms using a computer-assisted thresholding technique; all measures were square root-transformed. Energy-adjusted adolescent caffeine intake was estimated using the data from a food frequency questionnaire. Information regarding breast cancer risk factors was obtained from questionnaires closest to the mammogram date. We used generalized linear regression to quantify associations of caffeine intake with breast density measures. Results: In multivariable analyses, adolescent caffeine intake was not associated with any of the density phenotypes (caffeine 4th vs. 1st quartile: β = − 1.27, 95% CI − 4.62; 2.09, p-trend = 0.55 for percent density; β = − 0.21, 95% CI − 0.76, 0.34, p-trend = 0.65 for absolute dense area, and β = 0.23, 95% CI − 0.28, 0.74, p-trend = 0.50 for non-dense area). Additional adjustment of the models for body mass index at age 18 resulted in attenuation of the risk estimates. Conclusions: Our findings do not support the hypothesis that adolescent caffeine intake is associated with premenopausal mammographic breast density.