It's a sobering fact for millions of young women heading back to school: The more alcohol they drink before motherhood, the greater their risk of developing breast cancer. In a study published online this week in the Journal of the National Cancer Institute, researchers at Washington University School of Medicine say they have linked increased breast cancer risk to drinking. The study concluded that if a female averages a drink per day between early adolescence and her first full-term pregnancy, she increases her risk of breast cancer by 11 percent. The researchers also found that for every bottle of beer, glass of wine or shot of liquor consumed daily, a young woman increases her risk of benign breast disease by 15 percent. Although such lesions are noncancerous, their presence increases breast cancer risk by as much as 500 percent.