Prognosis Value of [¹⁸f] FDG-PET Prior Versus after Autologous Stem Cells Transplantation in High Grade Non-Hodgkin’s Lymphoma.

Positron emission tomography using fluorine 18-fluorodeoxyglucose (FDG-PET) is required in the assessment of therapeutic response in diffuse large B-cell lymphoma. Limited studies addressed the interest of FDG-PET prior autologous stem cells transplantation (auto-SCT) in High-grade non Hodgkin’s lymphoma (HG-NHL). Between April 2002 and December 2005, 42 HG-NHL (DLBCL in 35 cases and aggressive transformation in 7 cases) patients underwent auto-SCT in our institution and were systematicaly explored prior and after auto-SCT using computed tomography (CT) and FDG-PET. The therapeutic strategy included R-CHOP or R-DHAP as induction chemotherapy followed by auto-SCT. In note, auto-SCT was always included in the initial strategy and scheduled after completion of induction chemotherapy for patients at least in partial response (PR) according CT assessment. Pre-auto-SCT FDG-PET results did not influence the scheduled strategy. Auto-SCT was performed as part of the first-line therapy in 35 cases (83 %) or at the time of relapse in 10 cases. Prior auto-SCT, 14 patients were in PR and 24 in CR/Cru. Conditioning regimen consisted of BEAM in all cases (except one patient). The median follow-up (calculated from the time of auto-SCT) for living patients was 34,5 months [19–74 months]. The 2-years EFS and OS estimates were 79,6 % [63,2%; 89,3%] and 90,5 % [76,6%; 96,3%], respectively. According to pre and post auto- SCT FDG-PET results, patients were classified into 3 groups: NEG/NEG (n=25) POS/ POS (n=8) and POS/NEG (n=9). The 2-years EFS and OS estimates for NEG/NEG, POS/ POS and POS/NEG patients were 88 % versus 19 % versus 100 % (p= 0,0001) and 92 % versus 75 % versus 100 % (p = 0,19), respectively. According to FDG-PET response after auto-SCT, the 2-years EFS estimates for NEG versus POS patients were 90, 9 % versus 19 % (p<0,0001). In contrast, pre auto-SCT FDG-PET status has no prognosis value on both EFS (2-years EFS: 88% versus 65%) and OS (2-years EFS: 92% versus 88%). We conclude that only post and not pre-auto-SCT FDG-PET results has a prognostic value in HG-NHL. This result suggests that an pre-transplant intermediate positive FDGPET should not delay a scheduled ASCT which could clean off the negative value of an intermediate positive FDG-PET.