Low Predictive Value of Functional Imaging with ¹⁸FDG-PET or Gallium Scanning in Relapsed or Refractory Hodgkin Lymphoma Prior to Autologous Stem Cell Transplantation.

Introduction: ¹⁸FDG-PET early during first-line chemotherapy of Hodgkin Lymphoma (HL) has a high positive and negative predictive value. The predictive value of functional imaging (FI) in refractory or relapsed HL after salvage treatment and prior to high-dose (HD) chemotherapy and autologous stem cell transplantation (AUSCT) is less well established.

Methods: A retrospective analysis was undertaken of the clinical characteristics, FI results, event free survival (EFS) and over all survival (OS) data for 66 consecutive patients (pts) with refractory or relapsed HL treated with salvage chemotherapy and AUSCT between 1997 and 2007.

Results: The median follow-up was 52 months (range 0 to 125 months). Following salvage chemotherapy, and prior to AUSCT, 63 of the 66 evaluable pts (96%) had response assessment with a conventional CT scan, 53 pts also had FI with a gallium scan (n=18), ¹⁸FDG-PET scan (n=31) or both (n=4). Of the 53 pts with FI prior to AUSCT, 21 (40%) were in metabolic complete remission (FI-negative) and 32 pts (60%) had residual disease (FI-positive). The median EFS and OS for the whole cohort were 29 and 52 months, respectively. Median EFS was 31 and 13 months (p=0.096), and median OS was 60 and 39 months (p=0.35) for those with negative and positive FI, respectively. Significantly more pts with negative FI achieved CR with conventional imaging compared to those with positive FI (9/19 = 47% vs. 2/32 = 6%, p=0.001). Male pts were disproportionately represented in the cohort with positive FI (20/32) compared to the pts with negative FI (7/21, p=0.038). There was no association between FI-positivity and the clinical features of age, short duration (<12 months) of initial response, presence of B-symptoms or extranodal disease at the time of relapse, or the type of AUSCT conditioning used.

Conclusion: We did not demonstrate a strong predictive value of FI outcome prior to AUSCT for relapsed or refractory HL despite a trend for improved EFS for pts with negative FI. We did demonstrate that males had a higher rate of FI positivity suggesting this is also an adverse risk factor for failure of salvage therapy in relapsed/refractory HL.