The simplified follicular lymphoma PRIMA-prognostic index is useful in patients with first-line chemo-free rituximab-based therapy.

Follicular lymphoma (FL) is a heterogeneous disease; therefore, reliable prognostic tools are needed to plan treatment strategies. The FL International Prognostic Index (FLIPI) was developed before the rituximab era, while the PRIMA-PI was built on rituximab chemotherapy. Our objective was to evaluate these two prognostic tools in a cohort of 291 patients with FL treated in two prospective randomised Nordic Lymphoma Group trials with rituximab ± interferon. All patients had symptomatic/progressive disease and were previously untreated. The PRIMA-PI was prognostic for both time to treatment failure (TTF) and overall survival (OS) (log-rank P = 0·003 and P < 0·001, respectively). The PRIMA-PI high-risk identified a small group of patients with a very short TTF and OS compared to the low-risk group, with a hazard ratio (HR) of 1·90 (95% confidence interval [CI] 1·30-2·78, P = 0·001) and HR of 3·19 (95% CI 1·75-5·83, P < 0·001), respectively. The FLIPI risk groups were prognostic only for OS (log-rank P = 0·018). The simplified PRIMA-PI was valid in our FL cohort with first-line rituximab-containing chemo-free therapy and shows an improved risk stratification compared to the FLIPI, especially in patients aged >60 years. Patients in the PRIMA-PI high-risk group should be considered for alternative therapies.