One of the largest studies of its kind has found that women who drink alcohol are increasing their risk for breast cancer, according to researchers at the University of Chicago.

The team, which is presenting its findings at this week’s American Association for Cancer Research 2008 Meeting, found women who had even one or two drinks per day are still at high risk for the disease, but those who have three or more drinks, are increasing their odds by as much as 51 percent.

More than 70 percent of breast cancer tumors are classified as positive for both the estrogen and progesterone receptors, and alcohol influences those receptors, the researchers said.

"This suggests that a woman should evaluate consumption of alcohol along with other known breast cancer risk factors, such as use of hormone replacement therapy," said the study's first author, Jasmine Q. Lew, a fourth-year medical student at the University of Chicago.

Lew’s team said their analysis could not support a definitive conclusion as to whether alcohol influenced other types of breast cancer tumors.