It's a sobering thought for women who enjoy a few drinks at the end of a long day.
A new study has found that women who drink even moderate amounts of alcohol face a substantially increased risk - up to 50 per cent higher - of developing a common type of breast cancer.
"Even a drink a day can cause an increased risk," said Jasmine Lew, a fourth-year medical student at the University of Chicago who received a scholarship to conduct research at the National Cancer Institute in the United States.
The study, being presented at this week's American Association for Cancer Research annual meeting, seems to high- light the need for women to evaluate their levels of alcohol consumption.
Researchers examined data of nearly 185,000 postmenopausal women in the United States collected by the National Institutes of Health. About 70 per cent of women reported some level of alcohol intake. After following the women for seven years, researchers found that women who consumed three or more drinks a day had about a 50-per-cent increase in their risk for developing estrogen receptor positive, progesterone receptor positive breast cancer, which is one of the most common types.
Women who reported drinking one to two drinks a day had a 32-per-cent increase in breast cancer risk, while those who consumed, on average, less than one drink of alcohol a day had about a 7-per-cent increased risk.
"The more you drink, the higher your risk, the relative risk, of getting breast cancer," Ms. Lew said. "I think what should be taken from [the study] is that alcohol consumption is positively associated with breast cancer."
Although more research must be done to determine whether alcohol actually influences the development of breast cancer, the findings indicate a conclusive association between alcohol intake and possible risk, Ms. Lew said.
The findings appear to present further evidence that alcohol may increase the amount of estrogen metabolites in a woman's body, which may contribute to the development of hormone-sensitive breast cancer, according to the study.
The study is the latest in a growing collection of research that is demonstrating the significant consequences that alcohol can have on health.
"Alcohol is quite a toxic drug," said Tim Stockwell, director of the Centre for Addictions Research of British Columbia at the University of Victoria. "The sad fact is there are approximately 60 ways in which alcohol can kill a person or cause them to be very ill."
It's a growing problem in an era when binge drinking is increasingly socially acceptable, Dr. Stockwell said.
"Nearly all the provinces are going through a phase of increased consumption and have been across Canada for about the last 10 years," he said. "When that overall consumption goes up, drinking at all age groups tends to go up."
Numerous medical studies have found small amounts of alcohol have a positive effect on health and can protect against certain diseases. For instance, studies suggest that moderate amounts of red wine may reduce a person's risk of developing heart disease.
The problem is that people often drink beyond the small doses that could provide such benefits, Dr. Stockwell said.
He also said it's possible that some studies linking moderate consumption with positive benefits may be misleading, because people who report themselves as moderate to light drinkers may be more likely to be in good health than heavy drinkers.