Pre-Transplantation FDG-PET Is the Best Predictor for Outcome in Relapsed Lymphoma Patients Treated with Autologous Stem Cell Transplantation.

Intensive chemotherapy followed by autologous stem cell transplantation (ASCT) is the prefered treatment for young patients with chemosensitive relapsed aggressive lymphoma (NHL) and Hodgkin’s disease (HD). FDG-PET appears to be an excellent tool to evaluate chemosensitivity in lymphoma. In the present study we analyzed the predictive value for outcome of pre-transplantation PET as compared to initial prognostic factors at relapse.

Methods: Clinical and PET data from all consecutive patients with relapsed lymphoma (aggressive NHL and HD) were assessed. All patients were treated with DHAP-VIM-DHAP, followed by ASCT if responsive (at least PR based on CT after DHAP-VIM). Whole-body FDG-PET was performed after DHAP-VIM. Visual analysis was obtained in each scan and standardized uptake value (SUV) of the 3 most intense lesions in attenuation-corrected scans. Minimal follow-up after ASCT was 6 months. Predictive factors used were secondary age-adjusted IPI (sAAIPI) for NHL and secondary IPS (sIPS) for HD, duration of first remission and LDH at relapse. Univariate and multivariate Cox regression models and ROC analysis were used to assess predictive factors for relapse/progressive disease (PD) and Fisher’s exact test to assess relative risk.

Results: Between 1999 and 2003, 93 relapsed lymphoma patients were treated. 68/93 (73%) patients had responsive disease and ultimately 63/93 (68%) were transplanted. Post transplantation 36 (25 NHL and 11 HD) were in continued complete remission after a median follow up of 20 months.

PET was performed in 84 (63 NHL and 21 HD). All scans were used for visual assessment. SUV could be assessed in 70% of the scans. PET was positive in 76% and negative in 24% of the patients. Relapse/PD was observed in 44/64 (69%) PET-positive and only in 6/20 (30%) PET-negative patients (RR 5.1 (1.7–15.3), p=0.002).

SUV (p=0.001), sAAIPI/sIPS (p=0.023) and LDH (p=0.028) were predictive for outcome. In a multivariate Cox regression model adding separate parameters to SUV, no additional significant predictor was found. There was no difference between NHL and HD. ROC analysis showed a maximal predictive value at a SUV of 1.8 with a sensitivity and specificity of 0.66. A SUV ≥ 6.0 after DHAP-VIM was highly predictive for relapse/PD (spec. 0.95, sens. 0.27).

Conclusion: Pre-transplantation PET is the best predictor for outcome in patients with relapsed aggressive lymphoma as compared to other prognostic factors. Persisting lymphoma lesions on PET with a SUV ≥ 6.0 after reinduction chemotherapy predict progressive disease. Pre-transplantation PET may be helpful in the selection of patients for ASCT.