Treatment outcomes among high‐risk neuroblastoma patients receiving non‐immunotherapy regimen: Multicenter study on behalf of the Thai Pediatric Oncology Group

Background Neuroblastoma is the most common extracranial malignant solid tumor during childhood. Despite intensified treatment, patients with high‐risk neuroblastoma (HR‐NBL) still carry a dismal prognosis. The Thai Pediatric Oncology Group (ThaiPOG) proposed the use of a multimodality treatment to improve outcomes of HR‐NBL in non‐immunotherapy settings. Methods Patients with HR‐NBL undergoing ThaiPOG protocols (ThaiPOG‐NB‐13HR or ‐18HR) between 2013 and 2019 were retrospectively reviewed. Patient demographic data, treatment modalities, outcomes, and prognostic factors were evaluated and analyzed. Results A total of 183 patients with HR‐NBL undergoing a topotecan containing induction regimen were enrolled in this study. During the consolidation phase (n = 169), 116 patients (68.6%) received conventional chemotherapy, while 53 patients (31.4%) underwent hematopoietic stem cell transplantation (HSCT). The 5‐year overall survival (OS) and event‐free survival (EFS) were 41.2% and 22.8%, respectively. Patients who underwent HSCT had more superior 5‐year EFS (36%) than those who received chemotherapy (17.1%) (p = .041), although they both performed similarly in 5‐year OS (48.7% vs. 39.8%, p = .17). The variation of survival outcomes was observed depending on the number of treatment modalities. HSCT combined with metaiodobenzylguanidine (MIBG) treatment and maintenance with 13‐cis‐retinoic acid (cis‐RA) demonstrated a desirable 5‐year OS and EFS of 65.6% and 58.3%, respectively. Poorly or undifferentiated tumor histology and cis‐RA administration were independent factors associated with relapse and survival outcomes, respectively (p