Hypofractionated Proton Beam Therapy for Localized Residual or Recurrent Unresectable Hepatoblastoma.

BACKGROUND

We evaluated hypofractionated proton beam therapy (PBT) feasibility for unresectable hepatoblastoma (HBL).

OBSERVATIONS: Six patients with residual/relapsed localized HBL received PBT (50 to 60 Gy (RBE) in 10 fractions) between April 2019 and September 2024, with follow-up through September 2025. After 55-month follow-up, 5 patients remained alive without disease. One marginal recurrence was successfully salvaged by re-irradiation, and another bridged to hepatectomy (10% viable tumor). Toxicities were minimal, with one grade 2 duodenitis. One patient died of treatment-unrelated myelodysplastic syndrome while remaining HBL-free.

CONCLUSIONS

Hypofractionated PBT is a feasible, well-tolerated salvage option for refractory HBL, providing encouraging local control.