PFS rates stratified by ISS or R-ISS stage. (A) PFS stratified by ISS stage. Patients with ISS stage I had a median PFS of 44.4 months (95% CI, 39.6-68.5), ISS stage II had a median PFS of 38.3 months (95% CI, 36.4-55.1), and ISS stage III had a median PFS of 38.4 months (95% CI, 31.2-53.3). No statistically significant difference was observed between the 3 groups (log-rank P = .22). (B) PFS stratified by R-ISS stage. The median PFS was 78.9 months for R-ISS stage I, 39.8 months for R-ISS stage II, and 30.5 months for R-ISS stage III. No statistically significant difference was observed between the 3 groups (log-rank P = .077). The number at risk is shown below each plot.