A daily drink, whether it’s red wine, beer or liquor, may increase a woman’s risk of breast cancer, according to a study that suggests moderate drinking has similar ties to the disease as heavy alcohol consumption.
The study, which followed more than 100,000 women for 28 years, found that those who consumed three to six drinks a week had a 15 percent increased risk of breast cancer compared with those who didn’t drink. Two drinks a day increased the risk to 51 percent, according to the research published today in the Journal of the American Medical Association.
The study is the first to show that women who drink even moderate levels of alcohol over their lifetime can raise their chance of breast cancer, the researchers said. Previous research has shown that high levels of alcohol consumption raise the risk of the disease. In light of the findings, some women should consider cutting back their drinking, said Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York.
“It’s a modifiable factor because alcohol consumption is under a patient’s control,” Bernik, who wasn’t an author of the study, said today in a telephone interview. “If a woman does drink every day and they are at risk for breast cancer or if they want to reduce their risk for breast cancer, they should consider reducing their alcohol consumption.”
Alcohol may increase the hormone estrogen, which is implicated in breast cancer, Bernik said. Researchers don’t know for sure how alcohol boosts breast cancer risk, she said.
Breast Cancer Prevalence
About one in eight women will develop breast cancer over their lifetime, making it the most common cancer among American women except for skin cancers, according to the American Cancer Society. More than 230,000 new cases of the disease will be diagnosed this year, killing almost 40,000 women.
Researchers in the study followed 105,986 women who were part of the Nurses Health Study, from 1980 until 2008. The study looked to determine the risk of developing invasive breast cancer, the most common kind of tumor that grows in normal, healthy tissue.
Findings showed 7,690 women developed invasive breast cancer. Of those, 1,669 women didn’t drink, 3,143 drank less than three glasses a week and 1,063 drank the equivalent of three to six glasses of wine a week.
No increase in breast cancer risk was seen in the group who drank less than three glasses of wine a week compared with those who didn’t drink.
The amount of alcohol consumed from the ages of 18 to 40 and after age 40 were both associated with breast cancer risk, the study found. That’s probably because women don’t usually change their drinking habits over their lifetime, said lead study author Wendy Chen.
“When someone is thinking about their own drinking habits it’s not what they’ve been doing over the past month or the past year, it’s what someone has done over a long period of time,” Chen, a researcher at Brigham and Women’s Hospital in Boston and an assistant professor of medicine at Harvard Medical School, said today in a telephone interview.
Assuming U.S. women drank similar amounts as those in the Nurses’ Health Study and that changing behavior would lower breast cancer risk, about 17,200 breast cancers could be prevented each year by stopping alcohol consumption, Chen said. More study is needed to discover whether women can lower their breast cancer risk by stopping alcohol consumption, she said.
Steven Narod, a professor at the University of Toronto, who wrote an accompanying editorial in the journal, said doctors should add questions about alcohol consumption when assessing their patients for breast cancer risk. While the study doesn’t show that stopping drinking lowers a person’s risk of developing the disease, he said alcohol consumption may work similarly to hormone replacement therapy in which breast cancer risk declined two years after women stopped taking the therapy.
The Nurses’ Health Study, started in 1976, is one of the largest and longest running investigations into factors that influence women’s health. Its primary focus is the prevention of cancer, but has also produced data on heart disease, diabetes and other conditions.
The study was funded by the National Institutes of Health based in Bethesda, Maryland.