Hepatoblastoma (HB)and hepatocellular carcinomas (HCC) are the two most common primary malignant liver neoplasms in children. They constitute together about 0.5–1.5% of all childhood malignancies and their relative frequency is 0.5–1.5 cases per million per year among children.
Hepatoblastoma is by far the commonest histological subtype of primary malignant hepatic tumours occurring in children less than 15 years of age.Complete tumour resection is of paramount importance for cure, but operative mortality, without chemotherapy, has been reported to be as high as 10-20%. In addition, fewer than 50% of tumours are resectable at diagnosis and most patients with unresectable tumours die of progressive disease. The prognosis for hepatoblastoma has dramatically improved since the introduction in the 1980’s of effective chemotherapy – Cisplatin and Doxorubicin (PLADO) – capable of reducing the tumour volume and making previously unresectable tumours resectable. The operation also becomes safer and easier after pre-operative chemotherapy. Thirdly, there is no delay in treating metastatic disease, which is detectable at diagnosis in about 20% of patients.
Currently for 'standard' risk HB patients, i.e. those in whom the tumour has not spread outside the liver and involves, in the liver itself, either one, two, or three of the four sections of the liver, the main SIOPEL aim is to determine whether ototoxicity of the single agent Cisplatin can be prevented by the use of Sodium Thiosulfate (STS).
'High' risk HB patients, i.e. those patients with tumour throughout the whole of the liver, or whose tumour has spread beyond the confines of the liver, require more intensive chemotherapy treatment based on Cisplatin, Doxorubicin and Carboplatin with subsequent liver resection or transplantation. [See the SIOPEL guidelines for HR Hepatoblastoma]
Hepatocellular carcinoma is less common than HB in most areas apart from regions of endemic hepatitis type B, i.e., sub-Saharan Africa or South-East Asia. In some places (Papua New Guinea), HCC can be as frequent as 8.5% of all cancers. Unlike HB, HCC often develops in the presence of underlying liver disease and cirrhosis, especially viral hepatitis (mainly hepatitis B—HBv) or inborn metabolic errors (i.e., tyrosinaemia). HBv infection is the most common cause of childhood HCC in hyperendemic areas. However about 70-80% of HCC in developed countries occur ‘de novo’ without underlying predisposing liver condition. HCC is more often encountered in males and older children (10–14 years of age). Compared with HB, the prognosis in HCC is poor with long-term survival of 10–20% by most reports. Current treatment of pediatric HCC, recommended by the SIOPEL group, is based on PLADO protocol (DOXO + CDDP).