Alcohol intake and mammographic density in postmenopausal Norwegian women

Mammographic density is a strong risk factor for breast cancer. While alcohol intake has been associated with increased breast cancer risk, the association between alcohol consumption and mammographic density is not clear. We assessed the association between alcohol consumption and mammographic density among women who participated in the Norwegian Breast Cancer Screening Program in 2004. Mammographic density was assessed on digitized mammograms from 2,251 postmenopausal women aged 50-69 years, using a computer assisted method. Current intake of beer, wine (red and white), and liquor was assessed using a validated food frequency questionnaire. Non-drinkers were defined as complete abstainers (i.e., those who reported no intake of any type of alcohol). We used multivariate linear regression models to estimate least square means of percent mammographic density by categories of alcohol intake with adjustment for potential confounders. We also checked for possible effect modification by stratifying the analyses by age, body mass index, and hormone therapy. The mean percent mammographic density was almost similar for drinkers 18.3% (95% CI: 17.6-18.9%) and non-drinkers 17.8% (95% CI: 16.1-19.4%) (P = 0.59). There was no indication that amount of alcohol consumed was associated with percent mammographic density, with a mean percent density among women with the highest intake (>90 g of alcohol per week) of 18.2% (95% CI: 16.9-19.0%), only slightly different from that of non-drinkers 18.3% (17.3-19.6%) (P for trend = 0.99). There was no association between any type of alcohol consumed and mammographic density.There was no effect modification by body mass index, age, or hormone therapy use. We found no evidence of an association between alcohol intake and percent mammographic density.