Nov. 1, 2011
- Consumption of 3 to 6 alcoholic drinks per week is associated with a small increase in the risk of breast cancer, and consumption in both
earlier and later adult life is also associated with an increased risk, according to a study in the November 2 issue of the Journal of the
American Medical Association (JAMA). It also confirmed, however, that women
drinking two drinks a day had a 51 percent increased risk of breast cancer.
"In many studies, higher consumption of alcohol has been associated with an increased risk of breast cancer. However, the
effect of low levels of drinking, as is common in the United States, has not been well quantified," according to background information in the
article.
Most studies of
senior citizens in last 31 years show association between moderate
alcohol consumption and better cognitive function and reduced risk of
dementia
"In addition, the role of drinking patterns (i.e., frequency of drinking and 'binge' drinking) and consumption at
different times of adult life are not well understood."
Wendy Y. Chen, M.D., M.P.H., of Brigham and Women's Hospital and Harvard Medical School, Boston, and colleagues examined
the association of breast cancer with alcohol consumption during adult life, including quantity, frequency, and age at consumption.
The study included 105,986 women enrolled in the Nurses' Health Study who were followed up from 1980 until 2008 with an
early adult alcohol assessment and 8 updated alcohol assessments. The primary outcome the researchers measured was the risk of developing
invasive breast cancer.
During the follow-up period, there were 7,690 cases of invasive breast cancer diagnosed among the study participants.
Analyses of data indicated that a low level of alcohol consumption (5.0 to 9.9 grams per day, equivalent to 3-6 glasses of wine per week) was
modestly but statistically significantly associated with a 15 percent increased risk of breast cancer.
In addition, women who consumed at least 30 grams of alcohol daily on average (at least 2 drinks per day) had a 51
percent increased risk of breast cancer compared with women who never consumed alcohol.
The researchers also found that when examined separately, alcohol consumption levels at ages 18 to 40 years and after age
40 years were both strongly associated with breast cancer risk. The association with drinking in early adult life still persisted even after
controlling for alcohol intake after age 40 years.
Binge drinking, but not frequency of drinking, was also associated with breast cancer risk after controlling for
cumulative alcohol intake.
The authors add that although the exact mechanism for the association between alcohol consumption and breast cancer is
not known, one probable explanation may involve alcohol's effects on circulating estrogen levels.
"In summary, our study provides a comprehensive assessment of the relationship between alcohol intake and breast cancer
risk in terms of timing, frequency, quantity, and types of alcohol in a large prospective cohort with detailed information on breast cancer
risk factors," the researchers write. "Our results highlight the importance of considering lifetime exposure when evaluating the effect of
alcohol, and probably other dietary factors, on the carcinogenesis process. However, an individual will need to weigh the modest risks of
light to moderate alcohol use on breast cancer development against the beneficial effects on cardiovascular disease to make the best personal
choice regarding alcohol consumption."
Editorial: Alcohol and Risk of Breast Cancer
Steven A. Narod, M.D., of the Women's College Research Institute, Toronto, writes in an accompanying editorial that the
findings of this study "raise an important clinical question: should postmenopausal women stop drinking to reduce their risk of breast
cancer?"
"For some women the increase in risk of breast cancer may be considered substantial enough that cessation would seem
prudent. However, there are no data to provide assurance that giving up alcohol will reduce breast cancer risk.
Moreover, it would likely be easier for a woman who consumes 1 drink a week to stop drinking than for a woman who
consumes 2 drinks a day. Furthermore, women who abstain from all alcohol may find that a potential benefit of lower breast cancer risk is more
than offset by the relinquished benefit of reduced cardiovascular mortality associated with an occasional glass of red wine.
Exploration of the risk-benefit relationships between low levels of alcohol consumption and all-cause and cause-specific
morbidities and mortalities might be the topic of future analyses of the Nurses' Health Study and other prospective cohort studies."
Frequently Asked Questions About Alcohol
● What is a standard drink in the United States?
A standard drink is equal to 13.7 grams (0.6 ounces) of pure alcohol. Generally, this amount of pure alcohol is found in
> 12-ounces of beer.
> 8-ounces of malt liquor.
> 5-ounces of wine.
> 1.5-ounces or a shot of 80-proof distilled spirits or liquor (e.g., gin, rum, vodka, or whiskey).
● Is beer or wine safer to drink than liquor?
No. One 12-ounce beer has about the same amount of alcohol as one 5-ounce glass of wine, or 1.5-ounce shot of liquor. It
is the amount of alcohol consumed that affects a person most, not the type of alcoholic drink.
● What does moderate drinking mean?
There is no one definition of moderate drinking, but generally the term is used to describe a lower-risk pattern of drinking. According to the
Dietary Guidelines for Americans,1 drinking in moderation is defined as having
no more than 1 drink per day for women and no more than 2 drinks per day for men. This definition is referring to the amount consumed on any
single day and is not intended as an average over several days.
Two percent lower lung cancer risk with each glass of
red wine consumed per month