Neuroblastoma -5 years old kid

Hi everyone! Unfortunately, my nephew of 5 years old has been diagnosted with high risk neuroblastoma stage 4. We’re still waiting for the full pathology results but right now we’re very confused. The doctor offered an aggresive treatment plan and he starts chemeoterapy in 2 days. Any advices would be so helpful🙏🥺Please let me know how can we apply for a second opinion and what centers you recommend? Thank you😢