HealthDay News — Teenage girls and young women who drink even moderate amounts of alcohol may be increasing their risk for breast cancer, study data suggest.

Drinking 10 g of alcohol per day — the equivalent of about one drink — during adolescence was associated with a 21% increase (95% CI:1.01-1.45) in the risk for proliferative benign breast disease (BBD),Ying Lui, MD, PhD, of the Washington University School of Medicine in St. Louis and colleagues reported in Pediatrics.

Although noncancerous, BBD is a known risk factor for breast cancer, and previous studies have shown that women who drink are more likely to develop breast cancer than those who do not. Adult women who drink two to five alcoholic drinks a day have 1.5 times the risk of breast cancer compared to nondrinkers, according to the American Cancer Society. Researchers have suggested that the increased risk may be due to the limiting effect of alcohol on the amount of folate women are able to absorb.

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To further explore these associations, Lui and colleagues analyzed data from 29,117 women, who participated in the Nurses’ Health Study II and completed both adolescent alcohol consumption questions in 1989 and an adolescent diet questionnaire in 1998. They identified 659 cases of proliferative BBD from 1991 and 2001.

A dose-dependent association was observed between adolescent alcohol consumption and proliferative BBD, among women with low folate levels, with risk increasing with each 10 g/day increase in alcohol consumption (hazard ratio-1.15; 95% CI: 1.03-1.29). However, this number was not significantly different from the alcohol-associated risk among women with moderate and high folate intake during adolescence (P for interaction = 0.18), the researchers found.

“Adolescent alcohol consumption is associated with increased risk of proliferative BBD, which may not be reduced by increased folate intake during adolescence,” the researchers wrote. They noted that the study did not prove a cause-and-effect relationship.

Lui Y et al. Pediatrics. 2012; doi:10.1542/peds.2011-2601.