Young women who drink spirits—i.e., “hard liquor”—may be more prone to developing dense breast tissue than their peers who either stick to beer and wine or don’t drink at all.

The observation comes from Denmark, as Katja Kemp Jacobsen, PhD, of Metropolitan University College in Copenhagen and colleagues published their findings online Sept. 30 in Cancer Causes & Control.

The researchers used self-reported alcohol consumption and mammographic density (mixed/dense or fatty) as assessed at the first screening after patients were recruited between 1993 and 1997 into the Danish Diet, Cancer and Health study.

From this cohort they reviewed data on 5,356 women (4,489 post-menopausal) who attended mammographic screening in Copenhagen between 1993 and 2001.

The study group’s mean age was 56.2 years. More than half the women, 56.5 percent, had mixed/dense mammographic density. Some 91.8 percent were alcohol consumers.

The team used logistic regression to estimate associations between alcohol consumption and breast density.

In their fully adjusted model, the researchers found no association between current alcohol consumption and breast density at baseline; nor was there an association between the age of drinking initiation and breast density.

They found a “borderline statistically significant” increased odds ratio of having mixed/dense breast density in women who consumed more than seven drinks per week while in their 20s compared to non-drinkers in this age group.

Further, there was no effect on breast density from drinking while the women were in their 30s or 40s or older than 50.

However, when considering different types of alcohol, drinking spirits between the ages of 20 and 29 was positively associated with mixed/dense breast tissue as follows:

• three to seven drinks per week: odds ratio 1.74, 95 percent confidence interval 1.12 to 2.72; and
• more than seven drinks per week: odds ratio 1.76, 95 percent confidence interval 0.73 to 4.23.

While the connection between high hard-alcohol consumption in early adulthood and dense mammographic tissue was there in the numbers, Kemp Jacobsen et al. found no consistent pattern with beer, wine or fortified wine.