Overall survival of patients with low IPI risk, low-intermediate IPI risk, and high-intermediate plus high IPI risk as determined by the Follicular Lymphoma International Prognostic Index (FLIPI). (A) Low IPI risk. (B) Low-intermediate IPI risk. (C) High-intermediate and high IPI risk. Within each IPI risk group, the FLIPI can discriminate patients in groups with significantly different death risks.