PHOX2B and neuroblastoma: To validate sensitive neuroblastoma mRNA RT-qPCR BM testing, we prospectively assessed serial BM samples from 345 international high‐risk neuroblastoma patients, treated in trials NB2004 (GPOH) or NBL2009 (DCOG), using PHOX2B, TH, DDC, CHRNA3, and GAP43 RT-qPCR mRNA markers and BM GD2-immunocytology.