ECOG PS indicates Eastern Cooperative Oncology Group performance status; VEGF, vascular endothelial growth factor; EGFR, epidermal growth factor receptor.
The hazard ratio for death and corresponding 95% CI for each subgroup were estimated from unstratified Cox proportional hazards model with treatment as the only covariate. P values were calculated from the Cox model including treatment, subgroup factor, and subgroup factor × treatment interaction term.