TUESDAY, Nov. 1 (HealthDay News) -- Women who have as few as
three alcoholic drinks a week may have a moderately increased risk
of developing breast cancer, a new study finds.
Researchers analyzed data from nearly 106,000 women taking part
in the U.S. Nurses' Health Study to examine any links between
alcohol consumption and breast cancer. The women were followed from
1980 through 2008 and asked about their alcohol consumption about
every four years.
"We did see a modest risk [of breast cancer] associated with lower levels of alcohol consumption," said lead study author Dr. Wendy Chen, an assistant professor of medicine at Brigham and Women's Hospital and Harvard Medical School in Boston.
But Chen stressed that women who occasionally over-imbibe on
vacation or at a holiday party shouldn't be alarmed; the research
measured cumulative alcohol consumption over many years.
During the study period, about 7,700 women were diagnosed with
breast cancer. Women who reported drinking 5 to 9.9 grams of
alcohol daily (less than half an ounce a day or the equivalent of
three to six glasses of wine weekly) were 15 percent more likely to
develop breast cancer than women who never or rarely drank
Women who drank more -- about two glasses of wine, or 30 grams
of alcohol, daily -- had a 51 percent increased risk of breast
cancer. (Although the researchers converted grams of alcohol into
glasses of wine, the risk was similar whether women drank wine,
liquor or beer.)
The study is in the Nov. 2 issue of the
Journal of the American Medical Association.
Prior research has also found an association between alcohol
consumption and breast cancer. One reason for the connection may be
that alcohol raises levels of circulating estrogen, and high levels
of estrogen are linked to breast cancer, Chen said.
What made this study unusual is that information was provided
about women's alcohol consumption over several decades. Many other
studies have asked about alcohol consumption at a single point in
time, but drinking patterns may change over a lifetime, Chen
Researchers also looked at whether breast cancer risk varied
depending on when a woman drank -- either earlier in life (ages 18
to 40) or later in life -- but found it was the cumulative exposure
that made the most difference.
Binge drinking per se -- consuming at least six drinks in a
single day -- didn't seem to significantly add to breast cancer
risk. However, binge drinkers did tend to consume more alcohol
overall than other women, which upped the odds of breast
"It really is a cumulative average over a long period of time that gave the most consistent association with breast cancer risk," Chen said.
Researchers also analyzed average daily alcohol consumption
alongside other factors that could impact breast cancer risk, such
as family history and age, to make sure they were really getting at
the effect of alcohol. They found that women who drank a lot were
also more likely to smoke, although most studies have not found a
strong link between tobacco and breast cancer, Chen said.
Dr. Steven Narod, research chair in breast cancer at Women's
College Research Institute in Toronto, said the study was "well
"For breast cancer, it does seem the risks [of alcohol] start up at a lower level than we previously thought," Narod said.
But he urged women who drink regularly not to worry too much. "I
don't think I would worry about drinking one or two drinks a week.
If your average is five or six a week, I'm not sure that I would be
particularly worried about that, either. But 10 or more a week,
maybe," Narod said.
Previous studies have suggested a glass of red wine daily has
cardiovascular benefits, and those findings should not be
discounted, said Narod, who wrote an accompanying editorial in the
same journal issue.
"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," he wrote.
Moreover, the study authors said no evidence exists to show that
giving up drinking will
lower a woman's risk of breast cancer.
U.S. National Institute on Alcohol Abuse and
Alcoholism has more on women and alcohol.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
Copyright © EBSCO Publishing. All rights reserved.