Predictive value and clinical utility of centrally assessed ER, PgR, and Ki-67 to select adjuvant endocrine therapy for premenopausal women with hormone receptor-positive, HER2-negative early breast cancer: TEXT and SOFT trials - Regan, M M; Pagani, O; Francis, P A; SOFT and TEXT Investigators and International Breast Cancer Study Group (Breast Cancer Res Treat, 2015)