A novel risk stratification model based on the Children's Hepatic Tumours International Collaboration-Hepatoblastoma Stratification and deoxyribonucleic acid methylation analysis for hepatoblastoma

Introduction: Hepatoblastoma (HB) is the most common paediatric liver tumour, and epigenetic aberrations may be important in HB development. Recently, the Children's He-patic Tumors International Collaboration-Hepatoblastoma Stratification (CHIC-HS) devel-oped risk stratification based on clinicopathological factors. This study aimed to construct a more accurate model by integrating CHIC-HS with molecular factors based on DNA methylation. Methods: HB tumour specimens (N = 132) from patients treated with the Japanese Pediatric Liver Tumors Group-2 protocol were collected and subjected to methylation analysis by bisul-fite pyrosequencing. Associations between methylation status and clinicopathological factors, overall survival (OS), and event-free survival (EFS) were retrospectively analysed. We inves-tigated the effectiveness of the evaluation of methylation status in each CHIC-HS risk group and generated a new risk stratification model. Results: Most specimens (82%) were from post-chemotherapy tissue. Hypermethylation in > 2 of the four genes (RASSF1A, PARP6, OCIAD2, and MST1R) was significantly associated with poorer OS and EFS. Multivariate analysis indicated that > 2 methylated genes was an in-dependent prognostic factor (hazard ratios of 6.014 and 3.684 for OS and EFS, respectively). Two or more methylated genes was also associated with poorer OS in the CHIC-very low (VL)-/low (L)-risk and CHIC-intermediate (I) risk groups (3-year OS rates were 83% vs. 98% and 50% vs. 95%, respectively). The 3-year OS rates of the VL/L, I, and high-risk groups in the new stratification model were 98%, 90%, and 62% (vs. CHIC-HS [96%, 82%, and 65%, respectively]), optimising CHIC-HS. Conclusions: Our proposed stratification system considers individual risk in HB and may improve patient clinical management. (C) 2022 Elsevier Ltd. All rights reserved.