Heavier drinking three or more drinks a day - can increase risk up to 50 percent, according to researchers from Germany, France and Italy.
"Alcohol consumption is causally related with breast cancer," the study authors concluded after reviewing 113 prior studies. They attributed 2 percent of breast cancer cases in Europe and North America to light drinking alone, and about 50,000 cases worldwide to heavy drinking.
The research seems to confirm the expert advice for women to minimize drinking, said study leader Dr. Helmut Seitz, professor of medicine, gastroenterology and alcohol research at the University of Heidelberg in Germany.
The findings suggest that healthy women at average risk of breast cancer should not consume more than one alcoholic drink a day, the authors said.
"Women at an elevated risk for breast cancer should avoid alcohol or consume alcohol only occasionally," the researchers wrote. Those at increased risk include those with a family history of breast cancer.
The link between alcohol and breast cancer was first suggested in the early 1980s, the authors said. To update the research, they searched for studies published before November 2011. They found more than 3,400 studies in all and narrowed their focus to 113 that examined the effects of light drinking on breast cancer risk.
In the United States, one in eight women will develop breast cancer in her lifetime, experts estimate. The increased risk associated with drinking is added to that starting risk.
Alcohol is thought to increase estrogen levels, in turn, perhaps, increasing the risk of breast cancer. Several studies have found alcohol more strongly linked to cancers known as estrogen receptor positive, which require estrogen to grow.(Online news pk)
