EurekAlert! -- Researchers have developed and validated a model that predicts relapse in women with stage 2 or 3 breast cancer who have been treated with endocrine therapy prior to surgical removal of the tumor, according to a study published online September 23 in the Journal of the National Cancer Institute. The preoperative endocrine prognostic index (PEPI) may help identify women who can safely avoid chemotherapy and those women at high risk of relapse who should be considered for aggressive therapy.