Abstract
INTRODUCTION: Compared with standard chemotherapy, treatment of patients with relapsed aggressive lymphoma with high-dose chemotherapy and stem cell transplantation (HDC/ASCT) increases progression-free survival (PFS) and overall survival (OS). [18F]FDG-PET (PET) has been demonstrated to be more precise than conventional radiologic imaging techniques for restaging after chemotherapy [Kostakogu et. al. Euro J Nucl Med. 2000]. However, the value of PET, particularly posttransplant PET to predict clinical outcome after HDC/ASCT has yet to be established.
METHODS: We analyzed 44 patients who had histologically proven non-Hodgkin’s lymphoma (NHL), in first and subsequent relapse, sensitive to conventional-dose salvage chemotherapy, and had HDC/ASCT between April 1999 to June 2004 and PET as part of there disease evaluation, pre (6–8 weeks before) and/or post [early-30 days (D30) and late-100 days (D100)] HDC/ASCT. Thirty (68%) had DLBCL (diffuse large B-cell lymphoma), four (9%) FCCL (follicular center cell lymphoma), four (9%) T-cell lymphoma, three (7%) MCL (mantle cell lymphoma) and three (7%) TCR-BCL (T-cell-rich-B-cell-lymphoma). Log-rank analyses were done to compare PFS of PET positive and negative cases in (a) patients with DLBCL and (b) all histology combined.
RESULTS: Thirty patients (68%) had pretransplant PET and thirty-nine (89%) had posttransplant PET. Fourteen (32%) patients had positive pretransplant scans, while 21 (48%) had positive post-transplant PET-scans. Three patients died and one patient had progressive disease before day 30 and were excluded. Mean observation time of remission cases were 691 days (range 129-1916 days). Among DLBCL patients pre-transplant PET scan did not correlate with PFS (p= 0.1332, figure 1), while posttransplant PET correlated with PFS (D30-PET p=0.0019; D100-PET p=0.007, combined p <0.0001, figure 2). Amongst all histology’s, pretransplant PET-scan did not correlate with PFS, posttransplant PET-scans also showed a positive correlation with PFS (D30 p=0.0001; D100 p=0.0212 and combined p= 0.0001).
CONCLUSION: PET has an important prognostic role in evaluating response of patients following HDC/ASCT. In our analysis, posttransplant PET-scan showed positive correlation with PFS, and may be useful in detecting patients who need additional treatments as early as 30 days post-transplant. This finding however will need to be confirmed in a prospective study.
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