Primary aims:

1. Localized Disease: Groups B and C: To evaluate and validate the efficacy of sodium thiosulfate (STS) to reduce the hearing impairment caused by a cisplatin monotherapy in non-metastatic patients without adverse features (localized PRETEXT I-III tumors without positive VPEFR annotation factors) (Group B - treated with cisplatin mono-therapy) or with adverse features (localized PRETEXT I-III tumors with positive VPEFR annotation factors) (Group C - treated with regimen C5VD)
2. Metastatic Disease: Group D: To determine the 3-year Event-free survival (EFS) in patients with metastatic disease treated with International Society of Paediatric Oncology (SIOPEL 4) induction therapy followed by response adapted consolidation therapy.
3. To determine the 3-year EFS in patients with HB whose tumor is completely resected at diagnosis (Group A) and either receive no adjuvant chemotherapy (Group A1, completely resected well differentiated fetal (WDF) histology HB) or 2 cycles of standard dose cisplatin monotherapy (Group A2, completely resected non-well differentiated fetal histology HB)

Secondary aims:

1. To determine any impact of STS on chemotherapy response and survival in children with localized hepatoblastoma
2. To assess the feasibility of complete resection after 2 cycles of interval compressed lower dose cisplatin monotherapy (80 mg/m2/cycle) in non-metastatic patients and without adverse features
3. To assess the feasibility of complete resection after 2 cycles of C5VD in non-metastatic patients with adverse features.5. To determine the adherence to PRETEXT and Post-treatment extent of disease (POSTTEXT) based surgical guidelines
4. To determine the prognostic relevance in HB of a "small cell undifferentiated", tumor component, percentage of tumor necrosis in post chemotherapy specimens, and the relevance of a positive microscopic margin in resected HB specimens.
5. To determine the concordance between institutional, regional expert panel (prospective) and international expert panel (retrospective) review assessment of PRETEXT and POSTTEXT stage, and correlate with outcome variables.
6. To prospectively collect patient HB tumor, peripheral blood and urine specimens, for translational biology studies.