Background
Dosimetric and outcomes comparison study. Evaluated IMRT vs conventional/3D-CRT RT technique for primary-site RT in high-risk neuroblastoma. Aimed to determine whether IMRT can reduce dose to adjacent critical structures (kidneys, liver, spinal cord, gonads, vertebral bodies) while maintaining target coverage at 21.6 Gy.
Interventions and follow up
Arm A: IMRT to primary neuroblastoma site (21.6 Gy in 12 fractions of 1.8 Gy) using inverse-planned IMRT
Arm B: Conventional/3D-CRT to primary site (21.6 Gy, same dose/fractionation)
Primary endpoint: Dosimetric comparison — OAR doses (kidney V15, V18; liver mean dose; contralateral kidney Dmean)
mFollow up: 2.0 years (clinical outcomes)
Arm B: Conventional/3D-CRT to primary site (21.6 Gy, same dose/fractionation)
Primary endpoint: Dosimetric comparison — OAR doses (kidney V15, V18; liver mean dose; contralateral kidney Dmean)
mFollow up: 2.0 years (clinical outcomes)
Results
Kidney dose reduction (IMRT): Significant reduction in contralateral kidney V18 and Dmean vs 3DCRT
Liver mean dose: Reduced with IMRT
Local control: Equivalent between techniques (no inferiority demonstrated)
PTV coverage: Maintained ≥95% with IMRT
Liver mean dose: Reduced with IMRT
Local control: Equivalent between techniques (no inferiority demonstrated)
PTV coverage: Maintained ≥95% with IMRT
Adverse events
Main adverse events: IMRT: lower rates of late renal dysfunction and hepatic toxicity in dosimetric analyses. No significant differences in acute toxicity. Potential for increased low-dose bath with IMRT; secondary malignancy risk not fully characterized.
Conclusions
IMRT achieves equivalent target coverage and local control compared to conventional RT in neuroblastoma while significantly reducing dose to critical abdominal structures. IMRT is preferred technique for abdominal neuroblastoma RT when adjacent organ sparing is needed.
Key Limitations
Key Limitations: Retrospective dosimetric study; small sample size. Clinical outcomes not powered to detect differences in local control or late effects. Long-term follow-up insufficient to assess secondary malignancy risk from low-dose bath. Proton therapy may offer further OAR sparing.
Clinical Context
IMRT is now standard technique for neuroblastoma primary site RT at most centers, particularly when tumor abuts kidneys, liver, or spinal cord. Proton therapy is increasingly used to minimize dose to contralateral kidney and vertebral bodies in young children. COG ANBL1232 and subsequent trials incorporate modern RT techniques.
References