Prognostic value of PET-CT after frontline therapy in follicular lymphoma: A pooled analysis of central review in three multicenter studies.

8502 Background: The value of 18F-FDG PET-CT (PET) in response assessment after induction rituximab-chemotherapy for advanced stage symptomatic follicular lymphoma (FL) has recently been documented. To provide more precise survival estimates from a larger patient cohort with longer follow-up we conducted a pooled analysis of centrally reviewed scans in three studies. Methods: Patient data and conventional CT-based response assessment (IWC 1999) were recorded for all patients undergoing central PET review in the prospective multicenter GELA (PRIMA and PET Folliculaire), and FIL (FOLL05) studies. Scans were assessed independently by three reviewers applying the standardized Five-Point Scale (5PS). Postinduction PET status was compared with patient characteristics, CT-based assessment and survival endpoints of PFS and OS. Results: Of 246 scans performed at the end of the induction immunochemotherapy, 178 (27.6%) were positive with a cut-off ≥3 (FDG uptake >mediastinum), and 41 (16.7%) with a cut-off ≥4 (mode...