There were 565 events (progression or death) for the primary analysis, with 297 occurring in group 1 and 268 in group 2. The median follow-up time for progression-free survival among the 129 patients without an event was 35 months (range, 3 to 78) as of September 29, 2011. Data for 101 of the 694 patients (14.6%) were censored before the end of the 4-year follow-up period, primarily owing to the fact that, with a 28-month interval between the closure of data accrual and the final analysis, complete follow-up data on patients enrolled at the end of the trial would not have been available for the final analysis. The median progressionfree survival was 13.5 months (95% confidence interval [CI], 12.1 to 15.1) in the group that received anastrozole alone and 15.0 months (95% CI, 13.2 to 18.4) in the group that received the combination therapy (Fig. 2). The study objective, showing a significant improvement in the primary end point of progression-free survival with the combination therapy, was met (P = 0.007 with the use of a two-sided stratified log-rank test). Generally, the superiority of the combination therapy over anastrozole alone with respect to progressionfree survival emerged over time: at 1 year, the rate of progression-free survival was 57% with combination therapy and 56% with anastrozole alone; at 2 years, the corresponding rates were 35% and 28%, and at 3 years, the rates were 25% and 16% (Fig. 2). The hazard ratio for progression or death with the combination therapy was 0.80 (95% CI, 0.68 to 0.94), as calculated by means of a stratified Cox regression analysis.