The results are part of an ongoing study of more than 100,000 nurses who have been monitored for 30 years.
These types of studies can't give you any concrete answers but they can suggest certain associations.
The link between alcohol and breast cancer isn't new, but most previous studies found no increased risk for breast cancer among light drinkers. Now a study in this week's Journal of the American Medical Association (JAMA) shows just a few drinks a week may raise a woman's risk compared to women who don't drink at all.
Women in the study who drank three to six drinks per week had a 15-percent higher chance of developing breast cancer. And the risk increased by 10 percent for every 10 grams of alcohol consumed daily.
"Your alcohol intake does matter," said Dr. Deanna Attai, a breast cancer oncologist. "Whether it's one drink a day, whether it's three drinks a week, we don't really know what the minimum acceptable or safe level is, and that's going to be different for everybody."
Attai points out the study doesn't prove moderate drinking causes the disease, because many factors can lead to breast cancer.
"Women that have a higher alcoholic intake, maybe they're not as healthy in their diets. Maybe they're not exercising as much. Maybe they're not maintaining ideal body weight," said Attai.
Yet the studies on light drinking appear to go back and forth. Numerous studies show a glass of wine a day helps your heart health. So many women don't know what to make of the conflicting information.
Attai says the bottom line message is every woman's risk is different and the advice will not be the same for everyone.
"If you have a very strong family history of breast cancer, maybe you want to avoid alcohol completely," said Attai. "But I think that for most women, look at what you're doing and just see where you can make little tweaks to make yourself a little bit healthier."
It's important to note that this research, called an "observational study,"can be tough to interpret because it relies on people remembering how much they drank.
It doesn't take into account other factors, like genetics or general health.
As Dr. Attai points out: making healthier choices not only lowers your risk for cancer, but for other diseases like heart disease or diabetes as well.