Senior author Dr. Seema Khan, co-leader of the breast cancer program at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University and physician at Northwestern Memorial Hospital, said drugs such as tamoxifen and raloxifene are used to prevent breast cancer.
These drugs are used by women who are at high risk based on having a close relative with breast cancer, or certain types of benign change in the breast identified on biopsy, but the drugs are only effective against breast cancer that is sensitive to estrogen, known as hormone receptor-positive breast cancer.
They fail to prevent breast cancer that is not sensitive to estrogen -- hormone receptor-negative breast cancer.
"We now have the possibility of predicting if a preventive drug will work for a woman at high risk of breast cancer, so that we don't expose women to the risks and side effects of this drug if it won't help them," Khan said in a statement.
Until now, it was not possible to predict which of these two major types of breast cancer would occur in a particular high-risk woman and since these drugs also have side effects, many women chose not to take them, the researchers said.
The findings were published in the journal Cancer Prevention Research.