Even a small amount of alcoholic consumption -- as little as three drinks per week -- comes with a modest increased risk of breast cancer, a massive new study suggests.

While high alcohol consumption has long been associated with cancer risks, the study in the Nov. 2 issue of Journal of the American Medical Association, says as little as three to six drinks a week is linked to a 15 per cent increase in the risk of breast cancer.

The study, led by Dr. Wendy Chen of Harvard Medical School, also found that the best predictor for breast cancer risk was how much a person drinks over a lifetime, not how much the person drinks for a recent period of time.

"Our results highlight the importance of considering lifetime exposure when evaluating the effect of alcohol, and probably other dietary factors, on the carcinogenesis process," the researchers write.

The study involved 105,986 women between 1980 and 2008 whose alcohol consumption was compared to their risk of developing invasive breast cancer.

Women who had two or more alcoholic drinks per day in the study had a 51 per cent increased risk of breast cancer.

But Dr. Steven Narod of the Women's College Research Institute says the study shouldn't necessarily cause women to throw out their wine glasses.

"There (is) no data to provide assurance that giving up alcohol will reduce breast cancer risk," he wrote in an accompanying editorial.

He told CTV News that while there is an increased health risk for women who drink three or four alcoholic drinks a day, the health risk is mild for those women drinking just one glass a day.

"I don't think we would gain much by suggesting that they stop drinking altogether," he said. "Also, there are benefits from alcohol, particularly we think of red wine being healthy.'

He notes that red wine has long been linked to being beneficial to a person's cardiovascular health.

"I think this study was important because it did point that there is a message that alcohol increases the risk of breast cancer but I think for those who for those who drink one drink a day or less I would not go so far as to say they are posing a hazard to themselves as far as breast cancer risk."

The researchers say the exact causal link between alcoholic consumption and breast cancer isn't known but one possible explanation could be alcohol's effect on circulating estrogen levels.

They also note: "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 regarding alcohol consumption."

With a report from CTV's medical specialist Avis Favaro and producer Elizabeth St. Philip