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

Abstract

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 (SUV_max), total metabolic tumour volume and total lesion glycolysis were measured at baseline. The relative changes in SUV_max from baseline (ΔSUV_max) and the Deauville score were determined after induction.

Results: The population analysed comprised 36 patients with T-type LL. SUV_max 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). ΔSUV_max 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 SUV_max 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 ΔSUV_max may be useful for predicting therapeutic efficacy.

Keywords: 18F-FDG; Chemotherapy; Clinical trial; Lymphoblastic lymphoma; PET/CT; Prognostic factors.