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

ABSTRACT

BACKGROUND: In non-cutaneous T-cell/natural killer (T/NK) lymphomas, the prognostic value of (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) during or after therapy is unknown. PATIENTS AND METHODS: In 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). RESULTS: FDG-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. CONCLUSIONS: Although 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.