(ChemotherapyAdvisor) – Women at elevated risk for breast cancer — including positive family history, benign mastopathy, or other conditions — should avoid alcohol or consume alcohol only on occasion and all women should not exceed one drink per day, authors of a study in Alcohol and Alcoholism published online March 29 have recommended.
Seitz et al. from Germany and Italy found that low level or moderate drinkers, defined as one drink per day, had a 5% increased risk of breast cancer. Heavy alcohol consumption, defined as 3 or more drinks per day, increased risk of breast cancer 40% to 50%.
The authors reviewed research published before November 2011 via a literature search from MEDLINE, ISI Web of Science, and EMBASE. Of 3,431 articles retrieved, 113 papers reporting breast cancer risk estimates for light drinkers were included in the meta-analysis. This analysis included 44,552 cases in the reference category of non-drinkers and 77,539 cases in the light-drinking category; 51% of studies were from North America, 38% from Europe, 6% from Asia, and 10% from other regions.
The analysis showed a trend risk that was highly significant, with consistent evidence for a positive dose-risk relation between alcohol and breast cancer. High levels of alcohol consumption were associated with increased risk of breast cancer in the largest available studies.
“Since there is no threshold level of ethanol for breast cancer risk, the breast is one of the most sensitive organs for the carcinogenic action of alcohol,” they wrote. Alcohol increases estrogen levels, and estrogens may exert carcinogenic effects on breast tissue either via the estrogen receptor or directly. “Other mechanisms may include acetaldehyde, oxidative stress, epigenetic changes due to a disturbed methyl transfer, and decreased retinoic acid concentrations associated with an altered cell cycle,” they wrote.
Overall, alcohol drinking accounts for roughly 5% of breast cancers in Northern Europe and North America and up to 10% in countries such as Italy and France, where drinking alcohol is common among women.