Another study has reported that alcohol intake is associated with an increased risk for breast cancer, which is the leading cause of cancer death in Los Angeles County. A new study by European researchers has reported that consumption of more than one alcoholic beverage a day is associated with an increased risk for breast cancer. They published their findings on March 29 in the journal in the journal Alcohol Alcoholism.
The researchers focused on the relationship between light drinking and breast cancer. They defined light drinking as 12.5 grams of alcohol per day (i.e., one glass of wine or cocktail). The authors noted that even that amount presents some risk. “A significant increase of the order of 4% in the risk of breast cancer is already present at intakes of up to one alcoholic drink/day,” wrote the study authors, led by Helmut K. Seitz, PhD, from the Centre of Alcohol Research at the University of Heidelberg in Germany.
In November 2011, the investigators conducted a meta-analysis of medical literature that focused on light alcohol consumption. A meta-analysis is a compilation of data from a number of similar studies). The researchers found that a significant increase of about 4% in the risk of breast cancer existed at intakes of up to one alcoholic drink/day. Heavy alcohol consumption, defined as three or more drinks/day, was associated with an increased risk by 40–50%. The authors noted that this meant that up to 5% of breast cancers were attributable to alcohol in northern Europe and North America for a total of approximately 50,000 alcohol-attributable cases of breast cancer worldwide. They noted that 1–2% of breast cancers in Europe and North America are attributable to light drinking alone; they explained that among European and North American women, many more women were light drinkers rather than heavy drinkers.
The authors noted that alcohol increases estrogen levels, and estrogen may have a carcinogenic effect on breast tissue either via the estrogen receptors present in breast tissue or directly on the breast itself. They noted that other carcinogenic mechanisms include acetaldehyde, oxidative stress, epigenetic changes (changes in cell function) due to a disturbed methyl transfer (metabolism), and decreased retinoic acid (a metabolite of Vitamin A) concentrations associated with an altered cell cycle.
The authors concluded that women should not exceed one drink per day, and women at increased risk for breast cancer should avoid alcohol completely or consume alcohol only occasionally.
The present study supports the findings of a similar study, which was published in the November 2, 2011 issue of the Journal of the American Medical Association. The study, which was conducted by researchers at Brigham and Women’s Hospital and Harvard Medical School in Boston, Massachusetts, reviewed data from 105,986 women enrolled in the large Nurses’ Health Study. It reviewed “cumulative average consumption” over the 28-year study period. Participants were followed from 1980 to 2008, and completed eight updated alcohol-assessment questionnaires during that time.
Lead author Wendy Y. Chen, MD, MPH and colleagues noted that the study adds to the literature on the effects of alcohol consumption on breast cancer risk, particularly that of “low levels of drinking,” which “has not been well quantified. They added that, not surprisingly, larger amounts of alcohol consumption were associated with increased breast cancer risk over the study period. The researchers reported that the risk was statistically significant at levels as low as 5 to 9.9 grams per day, which is the equivalent to three to six drinks per week; however, they described this 15% increase in risk as “quite small.”
Drinking an average of 10.0 to 19.9 grams of alcohol per day (six to 12 drinks a week) resulted in a 22% increase in risk. Women who consumed 30 grams or more each day had a 51% increased risk, compared with drinking no alcohol at all. Drinking an average of 4.9 grams of alcohol a day over the study period was not associated with any significantly increased breast cancer risk, compared with never drinking. Dr. Chen noted that a little alcohol is okay; thus women should limit consumption to a few drinks per week or less. She suggested that alcohol amounts should be consumed strategically. For example, she explained, “if someone is on vacation or wants to ‘unwind’ by having a few extra drinks, they can offset that by drinking less at other time points.” The authors noted that, in making an individual decision about alcohol use, any breast cancer risk must be weighed against “the beneficial effects on cardiovascular disease.”