Lifestyle, behavioral, and dietary risk factors in relation to mammographic breast density in women at high risk for breast cancer.

Background: Women at high risk for breast cancer due to genetics or to risk factor profiles are counseled to adopt lifestyle, behavioral, and dietary changes to help reduce their risk. These recommendations are based on studies of women at average risk, so their effectiveness in high-risk women is unclear. Methods: We evaluated the impact of physical activity, smoking, alcohol consumption, and intake of folate and carotenoids on mammographic breast density-a proxy for breast cancer risk-among 387 high-risk women. Exposures were self-reported on questionnaires. Breast dense area, non-dense area, and percent dense area were measured from screening mammograms with Library for Breast Radiodensity Assessment software. Cross-sectional associations were estimated with multivariable quantile regression models. Results: After adjusting for age, adiposity, reproductive history, and use of postmenopausal hormones, no breast density measure was associated with physical activity level, smoking status, alcohol consumption, or estimated intake of folate, alpha carotene, beta carotene, lutein/zeaxanthin, and beta cryptoxanthin. Lycopene intake was associated with lower dense area when comparing the highest and lowest intake categories (adjusted difference in median= -14 cm2, 95% CI: -29 to 1.3 cm2). This association may be explained by incomplete adjustment for adiposity. Conclusions: Recommended lifestyle, behavioral, and dietary changes to mitigate personal risk of breast cancer do not substantially impact mammographic breast density measures. Impact: Alternative strategies, such as increased uptake of chemoprevention, may better serve risk reduction efforts in women at high risk for breast cancer.