18F-fluorodeoxyglucose–positron emission tomography before, during and after treatment in mature T/NK lymphomas: a study from the GOELAMS group

Abstract

BackgroundIn non-cutaneous T-cell/natural killer (T/NK) lymphomas, the prognostic value of 18F-fluorodeoxyglucose–positron emission tomography (FDG–PET) during or after therapy is unknown. Patients and methodsIn this retrospective study, 54 T/NK lymphoma patients were assessed using FDG–PET before (n = 40), during (n = 44) and/or after therapy (n = 31). ResultsFDG–PET showed an abnormal FDG uptake in all cases. Interim FDG–PET was negative in 25 of 44 cases. After completion of therapy, 19 of 31 patients reached complete remission with negative FDG–PET. In ALK+ anaplastic large cell lymphomas, the 4-year progression-free survival (PFS) was 80% and the negative predictive value of post-therapy FDG–PET was 83% (n = 9). In ALK- T/NK lymphomas, the 4-year PFS was 59% for patients with a negative interim FDG–PET versus 46% for patients with a positive interim FDG–PET (P = 0.28, n = 35). Similarly, there was no statistical difference in 4-year PFS between negative and positive post-therapy FDG–PET in these lymphomas (51% and 67%, respectively, P = 0.96). The 4-year cumulative incidence of relapse from a negative post-therapy FDG–PET was 53% in ALK- T/NK lymphomas. ConclusionsAlthough T/NK lymphomas are FDG-avid at diagnosis, a negative interim or post-therapy FDG–PET does not translate into an improved PFS in ALK- T/NK lymphomas.