Aim: Response to the therapy is one of the most valuable prognostic factors. The response evaluation is performed by computer tomography as a standard tool. The introduction of FDG-PET whole body imaging allows to discriminate viable tumor and fibrotic changes in structural abnormalities.
Methods: We have performed retrospective analysis of 96 patients with diagnosis of diffuse large B-cell lymphoma (1999-2004) who were treated by anthracyclin based chemotherapy and FDG-PET was performed as a part of intermediate restaging (after 2nd-4th cycle, 69 patients) or/and at the end of standard chemotherapy (68 patients).
Results: The progression free survival (PFS) and overall survival (OS) at 3 years were the endpoints. Median follow up was 30 months. The PFS and OS resp. for PET negative pts at intermediate restaging was 80.7% and 97.6% compared to the 50.5% and 71.5 % resp. for PET positive patients. The relapse risk and death risk for PET positive patients was 4.8 and 6.4 resp. The PFS and OS resp. for PET negative pts at the end of chemotherapy was 81.7% and 94.7% resp. compared to the 29.4% (p < 0.0001) and 57.5% (p < 0.0001) resp. for PET positive patients. The relapse risk and death risk for PET positive patients was 7.0 and 12.9 resp. Predictive value of PET at intermediate as well at the end restaging was observed in IPI low group as well IPI high risk subgroups for both PFS and OS, except OS in high risk subgroup at intermediate restaging.
Conclusion: The current analysis confirms predictive PET value for patients with DLBCL at intermediate as well at the end restaging. The question if and how to use the PET findings for tailoreing of therapy remains to be answered in prospective trials.