Prognostic significance of FDG-PET/CT in determining upfront autologous stem cell transplantation for the treatment of peripheral T cell lymphomas

This observational study aimed to evaluate the prognostic significance of interim and final ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (PET/CT) responses to upfront autologous stem cell transplantation (ASCT) in patients with peripheral T cell lymphomas (PTCLs). A total of 118 patients, from two independent institutions, with newly diagnosed PTCLs were enrolled, and 96 of them were evaluated. PET/CT was assessed at diagnosis, and during and after the primary treatment. Clinical outcomes of interim and final PET/CT were compared between transplanted and non-transplanted patients. The responses of PET/CT were assessed based on visual analysis using the Deauville five-point scale (5-PS). Clinicopathological features of transplanted patients (n = 37) were similar to those of non-transplanted patients (n = 59). After a median follow-up of 60.8 months, only final PET/CT response based on 5-PS was the independent prognostic factor of survival outcome (P < 0.001; HR 8.215; 95% C.I. 2.97–22.72) in multivariate analysis. Interim PET/CT response did not have a differential potential for predicting progression-free survival (PFS). In 59 patients, with score 1 or 2 in final PET/CT, the PFS rate was not significantly different between transplanted and non-transplanted patients (P = 0.970). Moreover, among the 37 patients with final PET/CT response score of 3–4, the PFS rate was equally poor in both transplanted and non-transplanted patients (P = 0.178). Final PET/CT assessment, based on 5-PS, was an important prognostic parameter for primary treatment of PTCLs, regardless of upfront ASCT. Interim PET/CT response could not be an indicator to determine the requirement for upfront ASCT.