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Research Summary

Alcohol Increases Breast Cancer Risk in Certain Women

The mechanisms by which alcohol may affect breast cancer risk are unclear. Using data from the Women’s Health Study, researchers examined the association between moderate drinking and breast cancer according to estrogen receptor and progesterone receptor status.

During an average of 10 years of follow-up, 1484 cases of breast cancer were documented among 38,454 women who were free of cancer and cardiovascular disease at baseline. Analyses were adjusted for potential confounders (e.g., age, body mass index, family history).

  • The risks of all breast cancers (invasive and in situ tumors) and invasive breast cancer were modestly higher in drinkers than nondrinkers and increased as drinking amounts increased (e.g., relative risks for all breast cancers, 1.0 for <0.5 drinks per day, 1.1 for about 1 drink per day, and 1.3 for about 2.5 drinks per day; P for trend=0.02).

  • These risks were limited to estrogen receptor positive and progesterone receptor positive tumors and strongest in women currently taking hormone replacement therapy.

  • Risks were similar across beverage type and not affected by folate intake.

Comments:

Like many previous reports, this analysis shows that alcohol intake is associated with a slight overall increase in the risk of breast cancer. The important findings are that the increase was (1) limited to estrogen receptor and progesterone receptor positive tumors and (2) strongest in current users of postmenopausal hormonal therapy. Unlike previous studies, this study did not show any protective effect of folate intake on breast cancer risk.

R. Curtis Ellison, MD

Reference:

Zhang SM, Lee I-M, Manson JE, et al. Alcohol consumption and breast cancer risk in the Women’s Health Study. Am J Epidemiol. 2007;165(6):667–676.


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