A study reported in the December issue of the journal Cancer Causes and Control finds drinking alcohol increases a woman's risk for breast cancer. In fact, in postmenopausal women, less than one drink a day can increase the risk of dying of breast cancer up to 30%, compared to non-drinkers.

"This is one more report showing that alcohol consumption increases the risk of breast cancer," said Heather Feigelson, PhD, senior epidemiologist at the American Cancer Society (ACS) and lead author of the study. "There are very few modifiable risk factors for breast cancer. Since this is one of the few that is modifiable, someone who is concerned about her risk for breast cancer should limit her consumption of alcohol."

The study looked at 242,010 women who answered questions about their lifestyle habits as part of the ACS Cancer Prevention Study (CPS II). Fourteen years later, 1,442 of those women had died because of breast cancer, and researchers analyzed the data to see if drinking led to an increased risk.

The research team found that any drinking increased the risk of death from breast cancer in post-menopausal women. However, they did not find an increased risk in pre- or perimenopauasl women.

"The evidence from this and other studies suggests alcohol consumption is not as important a risk factor for premenopausal women as it is for postmenopausal women," Feigelson said.

In the past, some studies suggested that wine might be less of a risk than hard liquor. However, this study looked separately at wine, beer, and liquor and found that each does lead to a similar degree of increased risk.

The amount matters; increased drinking means increased risk. Postmenopausal women who had one drink or less per day had a 30% higher rate of dying from breast cancer, compared to women who didn't drink at all. Women who drank more had a 40% increased risk of death from breast cancer.

What about past studies showing moderate drinkers have decreased risk for heart problems?

"Lifestyle decisions regarding the use of alcohol consumption should be balanced against the documented beneficial effects of moderate alcohol use for other chronic diseases," the authors wrote.

Each woman should discuss her decision about this with her primary care provider, Feigelson said.

"Take a careful look at your risk factors and your family history," she said. "Keep in mind we have lots of information about ways you can reduce your risk for both breast cancer and heart disease through exercise and proper diet."

The current study looked at the number of deaths due to breast cancer, while previous studies looked at whether drinking alcohol could increase a woman's chances of having breast cancer.

"There is very little literature on how alcohol consumption affects the chance of survival once someone has breast cancer," said Feigelson. "The issue of its effect on survival versus incidence needs more research."