Early alcohol consumption and breast fibroglandular density in adolescence: The growth and obesity Chilean cohort study

Background Alcohol consumption increases risk of breast cancer; however, the association of alcohol consumption on breast composition during adolescence is inconclusive. We evaluated the association of alcohol consumption with the percentage of fibroglandular volume (%FGV) and absolute fibroglandular volume (AFGV) of the breast in adolescent girls. Methods We conducted an analysis within a longitudinal cohort study (Growth and Obesity Chilean Cohort Study, n = 303). Alcohol consumption was assessed by the National Service for the Prevention and Rehabilitation of Drug and Alcohol Use (SENDA) questionnaire and breast density by dual-energy X-ray absorptiometry (DXA). We used linear regression models to evaluate the association between alcohol consumption (ever intake, age at first alcohol consumption, time of last consumption and quantity of consumption) and %FGV and AFGV adjusted for BMI z-score, birth weight, and maternal education. Results One hundred and twenty-six girls (42%) reported alcohol consumption (ever vs never) and 37% of them started before age 13. Adolescents who reported alcohol consumption had a higher %FGV compared to those who had never consumed (β = 3.9, 95% CI: 1.2, 6.7), and also in those who started consumption before the age of 13 years (β = 5.0, 95% CI: 1.1, 8.8). No significant associations was observed for AFGV. Conclusions Alcohol consumption during adolescence, particularly early initiation, was associated with breast fibroglandular composition. These findings are consistent with adolescence representing a potential window of susceptibility for breast cancer risk in adulthood.