Predictive value of 18F-FDG PET/CT in adults with T-cell lymphoblastic lymphoma: post hoc analysis of results from the GRAALL-LYSA LLO3 trial

Purpose We examined whether FDG PET can be used to predict outcome in patients with lymphoblastic lymphoma (LL). Methods This was a retrospective post hoc analysis of data from the GRAAL-LYSA LL03 trial, in which the treatment of LL using an adapted paediatric-like acute lymphoblastic leukaemia protocol was evaluated. PET data acquired at baseline and after induction were analysed. Maximum standardized uptake values (SUVmax), total metabolic tumour volume and total lesion glycolysis were measured at baseline. The relative changes in SUVmax from baseline (Delta SUVmax) and the Deauville score were determined after induction. Results The population analysed comprised 36 patients with T-type LL. SUVmax using a cut-off value of <= 8.76 vs. > 8.76 was predictive of 3-year event-free survival (31.6% vs. 80.4%; p = 0.013) and overall survival (35.0% vs. 83.7%; p = 0.028). Delta SUVmax using a cut-off value of <= 80% vs. > 80% tended also to be predictive of 3-year event-free survival (40.0% vs. 76.0%; p = 0.054) and overall survival (49.2% vs. 85.6%; p = 0.085). Total metabolic tumour volume, baseline total lesion glycolysis and response according to the Deauville score were not predictive of outcome. Conclusions A low initial SUVmax was predictive of worse outcomes in our series of patients with T-type LL. Although relatively few patients were included, the study also suggested that Delta SUVmax may be useful for predicting therapeutic efficacy.