Impact of Pre-Transplantation and Post-Transplantation Positron Emission Tomography (PET) Using 18-Fluorodeoxyglucose in Lymphoma Patients Treated with Autologous Stem Cell Transplantation.

Introduction : Assessment of therapeutic response using 18-Fluoro-deoxy-glucose (FDG) positron emission tomography (PET) is useful to determine prognosis in lymphoma. In poor prognosis lymphoma patients, it may have an important value in the pre-transplant evaluation and help to transplant-decision making. But the impact on patient outcome of post-transplant assessment is unknown.

Patients and methods: In our department, between July 2004 and December 2005, 60 consecutive patients (M/F ratio= 37/23) who achieved tumor response and received high-dose chemotherapy plus autologous-stem-cell transplantation (ASCT) were prospectively explored with PET, prior to ASCT (after 3–4 chemotherapy cycles) and 100 days after ASCT. PET images were evaluated without knowledge of conventional imaging and clinical history. Presence (PET positive) or absence (PET negative) of abnormal FDG uptake was related to event-free survival (EFS) and overall survival (OS).

Results :50 patients had non-Hodgkin lymphoma (20 diffuse-large-B-cell (DLBCL), 8 mantle-cell, 16 follicular, 4 T-large-cell, 2 Burkitt) and 10 Hodgkin’s lymphoma. Median age was 52 ranging from 19 to 68 years. At diagnosis, 9 patients had 2–4 performance status, 40 elevated LDH, 30 extranodal involvement and 53 staged 3–4. Tumor bulk was above 10 cm in 14 patients. 22 patients received front-line ASCT mainly after ACVBP (n=14) or CHOP. Platinum-based salvage chemotherapy (DHAP, n= 26) was the most frequently used for 27 relapses and 11 refractory diseases. 40 patients received Rituximab with chemotherapy. Prior ASCT, there were 31 complete remission (CR), 23 uncertain CR and 6 partial remission. Conditioning regimen was BEAM in 39 patients; Zevalin BEAM in11, Total Body Irradiation was used in 10. 44 patients (75%) were pre-ASCT-PET negative and 48 (80%) post-ASCT-PET negative. 6 patients (10%) converted from pre-ASCT-PET positive to post-ASCT-PET negative (2 Hodgkin, 1 mantle, 2 follicular, 1 DLBC) and 2 patients (3%) converted from pre-ASCT-PET negative to post-ASCT-PET positive (1 pulmonary infection, 1 early relapse in DLBC). One year after ASCT, 10 patients died (OS 80%) and 17 relapsed (EFS 67%). OS was estimated to 90% in pre-ASCT-PET-negative patients vs. 51 % in PET-positive (p=0.0003), EFS was 75% vs. 43%, respectively (p=0.001). OS was estimated to 87% in post-ASCT-PET-negative patients vs. 48% in PET-positive (p<0.0001), EFS was 77% vs. 25%, respectively (p<0.0001). There was no difference within histological subtypes or front-line vs. relapse/refractory. The only adverse prognostic factors in multivariate analysis was PET positive either pre ASCT (relative risk=4) or post ASCT (relative risk=12).

Conclusion: A positive PET after induction chemotherapy indicates a high risk of ASCT failure; in addition, this risk of failure is increased by a positive PET after ASCT. In pre-ASCT-PET-positive patients, more experimental approaches are needed. In pre-ASCT-PET-negative patients, post-ASCT-PET assessment may be omitted.