Alcohol consumption and mammographic density in the Danish Diet, Cancer and Health cohort

Purpose We examined the association between alcohol consumption and mammographic density (MD) considering in detail the time of exposure and the type of alcohol. Methods Of 5,356 women (4,489 post-menopausal) from the Danish Diet, Cancer and Health cohort (1993–1997) who attended mammographic screening in Copenhagen (1993–2001), we used MD (mixed/dense or fatty) assessed at the first screening after cohort entry. Alcohol consumption was assessed at the time of recruitment. Logistic regression was used to estimate associations [odds ratios (OR), 95% confidence intervals (CI)] between alcohol consumption and MD. Results The mean age was 56.2 years, 56.5% of women had mixed/dense MD, and 91.8% were alcohol consumers. There was no association between current alcohol consumption and MD at baseline (age 50–65, on average 1 year before MD assessment) neither between age at drinking initiation and MD, in the fully adjusted model. There was a borderline statistically significantly increased OR of having mixed/dense MD in women who consumed > 7 drinks/week at age 20–29 (1.31, 95% CI 1.00–1.72) compared to non-drinkers in this age group, and no effect of drinking at age 30–39, 40–49 or after > 50 years, when adjusting for current drinking. However, when considering different types of alcohol, drinking spirits at age 20–29 was positively associated with mixed/dense breast (3–7 drinks/week: OR 1.74, 95% CI 1.12–2.72); >7 drinks/week: (OR 1.76, 95% CI 0.73–4.23). No consistent pattern was found with beer, wine, or fortified wine. Conclusions We found higher MD among women with high alcohol consumption in early adulthood (ages 20–29), in those drinking spirits.