Inverse probability of censoring weighted Cox model results of the comparison of the monotherapy arms of Breast International Group 1-98 at median follow-up of 74 months. Comparisons for (a) primary and secondary endpoints and (b) subgroups with overall survival (OS) endpoint are shown. The size of the boxes is inversely proportional to the standard errors of the hazard ratio. The solid vertical line is placed at 0.82, which is the hazard ratio estimate for the overall analysis of the OS endpoint. CI, confidence interval; ER, estrogen receptor; L, letrozole; Nx, regional lymph nodes not examined; PgR, progesterone receptor; T, tamoxifen. *Other includes ER+/PgR unknown, ER unknown/PgR+, ER-/PgR- (ineligible), ER-/PgR unknown, and ER unknown/PgR unknown. Reprinted with permission from the Journal of Clinical Oncology . Copyright 2011, American Society of Clinical Oncology.