Early Pre/Post Fluoro-Deoxyglucose Positive Emission Tomography (PET) Does Not Predict Outcome of Patients Undergoing Hematopoietic Stem Cell Transplantation in Hodgkins Disease and Non-Hodgkins Lymphoma.

This study was designed to investigate the predictive value of early pre/post stem cell transplant (SCT) FDG-PET on outcomes in non hodgkins (NHL) or Hodgkins lymphoma (HL). We analyzed patients who received SCT for treatment of relapsed or refractory NHL or HL at Duke Medical Center between the years of 1996–2007. Patients who had either a FDG-PET scan following salvage chemo- or radio- therapy and within 14 weeks of transplantation (pre-PET)or a FDG PET scan within 6–14 weeks following transplantation (post-PET) were included in the analysis. PET was determined to be positive or negative based on chart review of radiology reports. Survival times are estimated using Kaplan- Meier method. Hazard ratios (HR) are from univariate Cox proportional hazards models. Overall survival (OS) was measured from the time of transplant until death, and for those patients still alive, it was censored at the last follow up date. Disease free survival (DFS) was measured from the time of transplant until first progression or death, whichever occurred first, and was censored at the date of last follow up for those alive without progression. A total of 102 patients were identified with PET in the appropriate time period. Median age was 48.5 (18–78); 71 patients had NHL, 31 patients had HL. Ninety-eight (96%) of the patients had chemosensitive disease, and had a documented PR (62) or CR (36) prior to transplant. The median DFS and OS of this population was 55 and 73 mo respectively. Median time to follow up was 38 mo (1.5 – 145 mo). Of the 75 pre-PET scans, 32 (43%) were positive; of the 78 post-PET scans, 22 (28%) were positive. At the time of this analysis, 28 (27%) of the patients had died from disease progression. There were 8 (10.6%) pre-PET, and 7 (9%) post- PET readings that were not clear. Our analysis revealed that neither pre-PET nor post-PET results were predictive of DFS (HR 1.73 p=0.16, HR 1.97 p = 0.052) or OS (HR 1.92 p=0.13; HR1.65 p=0.21). Further, for the patients who had measurable disease at the entry to SCT, post-PET was not predictive for DFS (HR 1.62, p=0.29) or OS (HR 1.59 p=0.35). Exclusion of unclear PET readings did not have any effect on these results. In subset analysis, post- PET did predict DFS in patients with NHL (HR 2.6 p=0.034). Our results suggest that early pre/post SCT PET analysis is not beneficial in this algorithm for predicting overall survival in these patients. Negative post-PET may predict DFS in patients with aggressive NHL, however, did not predict OS in this group. Our analysis indicates that other methods of determining risk of relapse and transplant outcome are needed.