Clinical characteristics of interim-PET negative patients with a positive end PET from the prospective HD08-01 FIL study.

FDG-positron emission tomography (PET) performed early during therapy in advanced Hodgkin lymphoma patients has been confirmed as being important for progression-free survival. A group of patients with a negative interim-PET (i-PET) showed a positive end induction PET (e-PET). The aim of this study was to evaluate the clinical characteristics of patients with a positive e-PET as a secondary end point of the HD0801 study. A total of 519 patients with advanced-stage de novo Hodgkin lymphoma received initial treatment and underwent an i-PET. Patients with negative results continued the standard treatment. i-PET negative patients were then evaluated for response with an e-PET and those patients found to have a positive one were also then given a salvage therapy. Among 409 i-PET negative, 16 interrupted the therapy, 393 patients were evaluated with an e-PET, and 39 were positive. Sixteen out of 39 underwent a diagnostic biopsy and 15 were confirmed as HD. Seventeen out of 39 e-PET were reviewed according to the Deauville Score and, in sixteen, it was confirmed positive (10 DS 5, 6 DS 4). With the exception of high LDH value at diagnosis (p = 0.01; HR 95% CI 1.18-4.89), no clinical characteristics were significantly different in comparison with e-PET negative patients. Positive e-PET after a negative i-PET has a worse outcome when compared with i-PET positive patients salvaged with therapy intensification. It was not possible to identify clinical characteristics associated with a positive e-PET.