Disease-free survival according to central and local classification of hormone receptor status. Kaplan-Meier estimates at a median follow-up of 4 years for 3,610 patients on the monotherapy arms of Breast International Group 1-98 with adequate tumor material for central assessment of hormone receptors. The two receptors are combined to define an overall assessment of hormone receptor status. Positive refers to estrogen receptor-positive or progesterone receptor-positive or both, and negative indicates that both are negative. DFS, disease-free survival; HR, hormone receptor; SE, standard error. Reprinted with permission from the Journal of Clinical Oncology . Copyright 2007, American Society of Clinical Oncology.