Small cell undifferentiated (SCU) histology and alpha-fetoprotein (AFP) levels below 100 ng/mL have been reported as poor prognostic factors in hepatoblastoma (HB); subsequent studies reported SMARCB1 mutations in some SCU HBs confirming the diagnosis of rhabdoid tumor. The Children's Hepatic tumors International Collaboration (CHIC) database was queried for patients with HB who had AFP levels less than 100 ng/mL at diagnosis or were historically diagnosed as SCU HBs. Seventy-three of 1605 patients in the CHIC database were originally identified as SCU HB, HB with SCU component, or HB with low AFP levels. Upon retrospective review, they were re-classified as rhabdoid tumors (n = 11), HB with SCU component (n = 41), and HB with low AFP (n = 14). Seven were excluded for erroneously low AFP levels. Overall survival was 0% for patients with rhabdoid tumors, 76% for patients with HB with SCU component, and 64% for patients with HB with AFP less than 100 ng/mL. Patients with HB with SCU component or low AFP should be assessed for SMARCB1 mutations and, if confirmed, treated as rhabdoid tumors. When rhabdoid tumors are excluded, the presence of SCU component and low AFP at diagnosis were not associated with poor prognosis in patients diagnosed with HB.

Background

Comparative assessment of treatment results in paediatric hepatoblastoma trials has been hampered by small patient numbers and the use of multiple disparate staging systems by the four major trial groups. To address this challenge, we formed a global coalition, the Children's Hepatic tumors International Collaboration (CHIC), with the aim of creating a common approach to staging and risk stratification in this rare cancer.

Methods

The CHIC steering committee-consisting of leadership from the four major cooperative trial groups (the International Childhood Liver Tumours Strategy Group, Children's Oncology Group, the German Society for Paediatric Oncology and Haematology, and the Japanese Study Group for Paediatric Liver Tumours)-created a shared international database that includes comprehensive data from 1605 children treated in eight multicentre hepatoblastoma trials over 25 years. Diagnostic factors found to be most prognostic on initial analysis were PRETreatment EXTent of disease (PRETEXT) group; age younger than 3 years, 3-7 years, and 8 years or older; α fetoprotein (AFP) concentration of 100 ng/mL or lower and 101-1000 ng/mL; and the PRETEXT annotation factors metastatic disease (M), macrovascular involvement of all hepatic veins (V) or portal bifurcation (P), contiguous extrahepatic tumour (E), multifocal tumour (F), and spontaneous rupture (R). We defined five clinically relevant backbone groups on the basis of established prognostic factors: PRETEXT I/II, PRETEXT III, PRETEXT IV, metastatic disease, and AFP concentration of 100 ng/mL or lower at diagnosis. We then carried the additional factors into a hierarchical backwards elimination multivariable analysis and used the results to create a new international staging system.

Results

Within each backbone group, we identified constellations of factors that were most predictive of outcome in that group. The robustness of candidate models was then interrogated using the bootstrapping procedure. Using the clinically established PRETEXT groups I, II, III, and IV as our stems, we created risk stratification trees based on 5 year event-free survival and clinical applicability. We defined and adopted four risk groups: very low, low, intermediate, and high.

Interpretation

We have created a unified global approach to risk stratification in children with hepatoblastoma on the basis of rigorous statistical interrogation of what is, to the best of our knowledge, the largest dataset ever assembled for this rare paediatric tumour. This achievement provides the structural framework for further collaboration and prospective international cooperative study, such as the Paediatric Hepatic International Tumour Trial (PHITT).

Funding

European Network for Cancer Research in Children and Adolescents, funded through the Framework Program 7 of the European Commission (grant number 261474); Children's Oncology Group CureSearch grant contributed by the Hepatoblastoma Foundation; Practical Research for Innovative Cancer Control and Project Promoting Clinical Trials for Development of New Drugs and Medical Devices, Japan Agency for Medical Research; and Swiss Cancer Research grant.

BACKGROUND: In the treatment of resectable hepatoblastoma (HB), it has not been established whether upfront surgery (UF) at diagnosis or neoadjuvant chemotherapy and delayed surgery (DL) is preferred. We compared patients with localized HB who underwent either UF, or DL after neoadjuvant chemotherapy in the Childrens Hepatic tumors International Collaboration (CHIC) database of 1605 cases enrolled in eight multicenter hepatoblastoma trials between 1988 and 2010. METHODS: Among the 512 resectable HB patients who had PRETEXT (PRETreament EXTent of disease) I or II unruptured tumors at diagnosis without extrahepatic invasion, distant metastases, or massive vascular invasion, 172 underwent UF and 340 underwent DL. The primary outcomes were event-free and overall survivals after start of treatment in these two groups. Survival analysis was performed using the Kaplan-Maier analysis with long-rank tests and multivariable Cox regression models. FINDINGS: Complete resection rates were comparable (93.6% in UF and 89.7% in DL). The total cycles of chemotherapy of DL (median:6) were significantly more than those of UF (median:4) (P < 0.01). The 5-year event-free survival (EFS) was 90.6% and 86.6% (P = 0.89) in the UF and DL cohorts, respectively. The surgical complications, recurrence rates, and late complications were not significantly different between the cohorts but the EFS rates of DL patients with a low alpha-fetoprotein (AFP) level (100-999 ng/mL) or older age at diagnosis (≥3 years old) were significantly worse than others. INTERPRETATION: The outcomes, surgical resectability, and complications were not significantly different between the UF and DL groups. Eligible patients with a low AFP level (<1000 ng/mL) or older age (≥3 years old) showed better outcomes in the UF group and might be considered for initial resection. FUNDING: European Network for Cancer Research in Children and Adolescents, funded through the Framework Program 7 of the European Commission; Childrens Oncology Group Cure Search grant contributed by the Hepatoblastoma Foundation; Practical Research for Innovative Cancer Control and Project Promoting Clinical Trials for Development of New Drugs and Medical Devices, Japan Agency for Medical Research and Development; Japan Society for the Promotion of Science; and Swiss Cancer Research grant.