Benign and Malignant Liver Tumors in Children

Abstract

This overview of pediatric liver tumors is presented with an emphasis on the two most common tumors, hepatoblastoma (HB) and hepatocellular carcinoma (HCC). Other major benign and malignant liver tumors of childhood are summarized. The most exciting recent advances in HB and HCC is the Pediatric Hepatic International Tumor Trial (PHITT study), which opened to international enrollment in 2018. This study is being conducted as an international collaborative trial with the International Liver Tumors Strategy Group (SIOPEL), Children's Oncology Group (COG), and Japanese Children's Cancer Group (JCCG). This global effort has been catalyzed over the last 10 years by the Children's Hepatic tumor International Collaboration (CHIC). For HB CHIC was able to construct a large database comprised of eight multicenter trials from around the world, which was used to develop a new unified global risk stratification system. At the same time our pathology colleagues established a new international histopathological consensus classification for pediatric liver tumors and our radiology colleagues established a new 2017 international collaborative update of the PRE-Treatment EXTent of disease (PRETEXT) radiographic-based staging system. Concomitantly there have been advances in HB chemotherapy options, in the sophistication of our radiographic imaging, in percutaneous and endovascular treatment approaches, in surgical technique, and in our understanding of the role of liver transplantation for unresectable tumors. These achievements, along with identification of new biologic markers, treatment intensification for poor risk tumors, and chemotherapy reduction for low-risk tumors, are being tested and validated in the PHITT trial. Although chemotherapy advances have been more modest in HCC, effective vaccination programs for hepatitis B have shown a decreasing HCC incidence in areas of endemic hepatitis B virus. Complete resection is the strongest predictor of good outcome, and liver transplantation has increasingly become a viable option for selected children with HCC without extrahepatic disease. The role of new drugs targeting genomic pathways in pediatric HCC may become clear in future collaborative studies.