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Study: Light drinking raises breast-cancer risk

By Misti Crane

As few as three drinks a week can increase a woman’s risk of developing breast cancer, according to a study published today.

The information comes from the Nurses’ Health Study, which followed nearly 106,000 women from 1980 until 2008.

The relationship between alcohol and breast cancer already is established. But this large study shows a link between lighter drinking — levels that many women have been told will help their hearts — and increased risk of the disease.

The research appears in this week’s Journal of the American Medical Association.

For women who had one drink a day, the risk was about 1.2 times higher than expected, and their 10-year risk increased from 2.8 percent to 3.5 percent. For women who drank two or more drinks a day, the risk was about 1.5 times higher, corroborating previous research linking higher consumption with breast cancer.

Even as experts welcome more data on the connection between alcohol and breast cancer, they caution that the study isn’t enough to drastically change the advice doctors give women, particularly considering the cardiovascular benefits of light drinking.

Furthermore, the study provides no evidence that quitting drinking will do a lighter drinker any good.

“Basically this stuff leads to more confusion,” said Dr. Peter Shields, deputy director of the Ohio State University Comprehensive Cancer Center and president of the American Society of Preventive Oncology.

Shields said it might provide food for thought for women who know they’re at an elevated risk of developing breast cancer, especially those who’ve already had the disease once.

“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,” the study authors wrote.

They found a modest association between binge drinking and breast cancer. That’s something that might be useful for younger women to know, said Dr. Angie Larsen, a breast surgical oncologist at Mount Carmel St. Ann’s hospital.

Larsen said the study also, importantly, confirmed that cumulative alcohol consumption during a woman’s lifetime plays a role in cancer risk.

“We do know the more you drink throughout your life — your total alcohol consumption — can have an impact on your risk,” she said.

It’s important to remember that alcohol consumption is just one risk factor among several, said Dr. Mark Cripe, program director of the breast surgery fellowship at Grant Medical Center.

Staying at a healthy weight after menopause, exercising and eating a low-fat diet all can reduce risk, he said.

Cripe said one interesting finding in the study was that frequency of drinking wasn’t important — that six half glasses of wine six days in a row was no different than three glasses on the weekend.

Scientists don’t know exactly how alcohol contributes to cancer, but the study authors said that one probable explanation would be that alcohol affects estrogen levels. The study found no difference based on the type of alcohol.

In an editorial that accompanied the research, Dr. Steven Narod of the Women’s College Research Institute in Toronto said that the research probably isn’t applicable to women of any age, only those with postmenopausal breast cancers.

“However, this should not imply that alcohol use in the early adult years is innocuous,” he said. Narod suggested more research into the risks and benefits of light to moderate drinking.