Dietary associations with breast density in women on adjuvant Tamoxifen therapy within the Diindolylmethane Efficacy (DIME) Study

Abstract

Breast density (BD) describes the distribution of epithelial and connective versus fatty tissue; higher BD is a predictor of higher breast cancer risk. Tamoxifen (TAM) is a commonly prescribed anti‐estrogen adjuvant cancer treatment to reduce breast cancer risk, partially through modulation of breast density. Dietary components, including fiber, fat, and total energy intake, potentially influence BD. The relationship between dietary intake and BD in women prescribed TAM is not fully understood. We conducted a cross‐sectional analysis using baseline data collected from 130 pre‐ and post‐menopausal women taking TAM and enrolled in the Diindolylmethane Efficacy (DIME) Study. BD was measured from digital mammograms, and participants completed the Arizona Food Frequency Questionnaire to assess dietary intake. Mean BD was 25% ± 15%. Linear regression examining dietary exposures of intake and adjusted for age, time on TAM, menopausal status, and body mass index (BMI) indicated no significant association between BD and total energy intake. No other associations between dietary factors and BD were observed, including total fat, protein, and carbohydrate intake as well as intake of fiber, fruit, vegetables, cruciferous vegetables, and alcohol. Dietary intake shows little association with BD among women taking TAM therapy. Alternate preventive mechanisms for diet in women on TAM therapy should be investigated, including potential effects on estrogen and TAM metabolism.Support or Funding InformationSupported by National Institutes of Health (NIH), National Cancer Institute (NCI) funding under 1R01CA149417‐01A1 (Thomson‐PI) and the University of Arizona Comprehensive Cancer Center Support grant funded by NIH‐NCI grant #CCSG‐CA023074 (Alberts‐PI).