External validation of the composite predictor in fixed samples by quantitative real-time PCR. Kaplan-Meier estimates of PFS (panels A and C), and OS (panels B and D) for strata defined by the IPI (panels A and B) or by prospectively defined thresholds of a composite model integrating the TGS and IPI (TGS-IPI; panels C and D). The 3 TGS-IPI strata correspond to a priori–defined thresholds depicted in Figure 3E (high risk, TGS-IPI > 4.51; intermediate risk, 4.51 ≥ TGS > 3.47; and low risk, TGS ≤ 3.47). Depicted P values reflect log-likelihood estimates. All depicted associations were also significant by log-rank product limit tests of Kaplan-Meier strata, including between TGS-IPI and PFS (P < .0001, HR 3.9, 95% CI 2.4-6.3; panel C) and between TGS-IPI and OS (P < .0001, HR 3.7, 95% CI 2.2-6.2; panel D). Inset pie charts reflect distribution of risk groups as defined by the IPI or TGS-IPI, with color coding corresponding to Kaplan-Meier curves.