Aim/purpose: (123)I-meta-iodobenzylguanidine ((123)I-mIBG) scintigraphy is well established for staging and evaluation of response in children with high-risk neuroblastoma but its prognostic value in highly intensive first-line treatment protocols is uncertain. The presence of any (123)I-mIBG positive tumour tissue was correlated with event-free survival (EFS) and overall survival (OS).
Patients and methods: The prognostic impact of residual (123)I-mIBG uptake into the primary tumour and metastases for predicting outcome in 113 stage 4 neuroblastoma patients >1 year of the German Neuroblastoma Trial NB97 was assessed using a univariate log-rank test and multivariate Cox regression analysis.
Results: All patients had (123)I-mIBG positive disease at initial staging. After four courses of induction chemotherapy, 71% of patients were still (123)I-mIBG positive for the primary tumour and 61% for metastases. After six courses, 39% of patients had (123)I-mIBG uptake by the primary tumour and 45% residual (123)I-mIBG positive metastatic disease. The (123)I-mIBG status of the primary tumour site had no bearing on outcome. Residual (123)I-mIBG positive metastatic disease after four (3-y-EFS 25.7+/-5.3% versus 55.9+/-7.6%, p=0.009; 3-y-OS 49.8+/-6.1% versus 65.0+/-7.3%; p=0.021) and after six chemotherapy cycles (3-y-EFS 27.5+/-6.2% versus 47.4+/-6.4%, p=0.011; 3-y-OS 50.5+/-7.1% vs 60.0+/-6.4%, p=0.031) was associated with poor outcome.
Conclusion: Functional imaging with (123)I-mIBG scintigraphy can identify poor responders with any persistent metastatic (123)I-mIBG uptake who are at a high risk of disease relapse. (123)I-mIBG response of the primary tumour site had no bearing on outcome.