Prognostic value of 18F-DOPA PET/CT at the time of recurrence in patients affected by neuroblastoma

Purpose The aim of this study was to investigate the relationship between I-123-metaiodobenzylguanidine (MIBG) scan semi-quantification and a new F-18-DOPA positron emission tomography (PET)/CT score in patients with suspected or documented neuroblastoma (NB) relapse and to assess the association between these two parameters and progression-free survival (PFS)/overall survival (OS). Methods We analysed 24 NB patients who had undergone I-123-MIBG and F-18-DOPA PET/CT scans at the time of suspected relapse, after applying a proper scoring system for each scan. In time-to-event analyses, the score distributions were regarded as continuous and were categorized in tertiles and medians. We used Kaplan-Meier curves and Cox proportional hazard models for PFS and OS in order to estimate the independent prognostic impact of I-123-MIBG and F-18-DOPA PET/CT scans. Results The I-123-MIBG and F-18-DOPA scores were highly and positively correlated (Spearman's rho = 0.8, p < 0.001). Over a median follow-up of 14 months (range 6-82), 12 cases of disease progression and 6 deaths occurred. Multivariate Cox models showed a higher risk of disease progression [hazard ratio (HR) 17.0, 95 % confidence interval (CI) 2.7-109] in NB patients with I-123-MIBG score > 3 (3rd tertile) and an even higher risk (HR:37.2, 95 % CI 2.4-574) in those with F-18-DOPA whole-body metabolic burden (WBMB) > 7.5 (median), after adjustment for all main clinical/pathological factors considered. Kaplan-Meier analyses showed a significant association with OS (log-rank p = 0.01 and p = 0.03 for I-123-MIBG and F-18-DOPA WBMB, respectively). Conclusion Our results confirm the good agreement between F-18-DOPA PET/CT and I-123-MIBG scan in patients affected by NB relapse. In time-to-event analyses, I-123-MIBG scan and F-18-DOPA PET/CT scores were independently and significantly associated with disease progression.