In this issue of Clinical and Molecular Hepatology, Kim and colleagues [11] investigated the predictive power of methylation markers in HCC de novo recurrence (>1 year) post-surgery. In order to identify more accurately specific Methylation signatures of de novo recurrence in patients with HCC, the authors classified patients into low- and high-risk groups based on Infinium Methylation EPIC array analysis and a machine learning approach on 140 samples in the discovery cohort. Then, the Methylation markers were validated using a methylation-sensitive high-resolution melting (MS-HRM) assay. They found that the high-risk recurrence group (Methylation Group 2; MG2) had a lower average methylation level (0.17 vs. 0.73) with a higher recurrence rate (23.5% vs. 44.1%) than the low-risk group (MG1). Moreover, the MS-HRM assay confirmed its effectiveness in predicting de novo recurrence with 95.5% sensitivity, 89.7% specificity, and 92.2% accuracy. Furthermore, while in combination with several clinically significant factors using Kaplan-Meier analysis for RFS, such as high AFP levels, positive alcohol consumption history, and vascular invasion, the methylation group in the high-risk group was associated with high recurrence.

DNA methylation plays a key role in regulating various biological processes, including transcription and post-transcriptional processing, posttranslational modification, chromatin remodeling, genomic imprinting, X chromosome inactivation, and inhibition of repetitive DNA elements [12]. Growing evidence reveals that tumor DNA methylation profiles could provide distinct and reproducible signatures to predict tumor recurrence in different tumors [13,14]. As is well recognized, tumor DNA methylation profiles are stable in both biological and chemical processes, in turn making it easier to be performed in routine clinical settings. On one hand, DNA methylation data exhibit good technical stability across different experiments. On the other hand, methylation profiles can be efficiently assayed in retrospective studies using fresh-frozen tissue samples or paraffinrmbedded archival materials [12]. Four critical methylation markers: cg21325760 (MAGEL 2), cg1054 4510, cg06702718, and cg15997204 (MYT1L) had strong predictive performances, showing good Area Under the Curve (AUC 90.8–96.5%), sensitivities (85.0–89.7%), and specificities (79.1–88.6%) in discovery cohort, respectively. Quadruple-marker panels achieved the highest performance (AUC 97.7%) compared with dual-marker panels (96.8%) and triple-marker panels (97.3%). These results suggest that the four methylation markers may jointly participated in early carcinogenesis, subsequently contributing to the development of HCC.

The prognostic model usually established by combining clinical factors with biological markers is currently the main strategy for predicting tumor recurrence. In the multivariate analysis, tumor stage was also identified as a significant factor in two cohorts including TCGA cohort (HR 1.87, 95% CI 0.93–3.33; P=0.034) and Validation Cohort 2 (HR 6.94, 95% CI 1.43–33.63; P=0.016). The methylation group remained a significant predictor of RFS in the discovery cohort (HR 1.87, 22 95% CI 1.02–3.43; P=0.042) and Validation Cohort 1 (HR 2.04, 95% CI 1.05–3.96; P=0.036) and Validation Cohort 2 (HR 2.99, 95% CI 1.01–8.92; P=0.049). These data reveal that a higher degree of epigenetic disruption in tumor, especially on late tumor stage, potentially provide a good soil in the tumor microenvironment that cultivates and promotes de novo cancer cell development.

Notably, with advances in immunotherapy like CARES-310 [15] and IMbrave150 trials [16], more HCC patients may benefit from new immune- and targeted therapies, or better non-surgical treatment options, which in turn may fundamentally change current anti-cancer strategies. Even if these revolutionary advances, tumor recurrence is always one of the most important factors in these regimens to deteriorate the prognosis of HCC patients. Interestingly, tumor DNA methylation profiles provide not only prognosis information but also distinct reproducible signatures of tumor-infiltrating immune phenotypes and immune status in solid tumors [17], potentially influencing immunity and recurrence risk. At present, the question of whether the impact of DNA methylation associated immunotherapy use confers additional survival benefit in patients with HCC needs to be elucidated. More well-designed preclinical and clinical studies are required to explore the mechanism of DNA methylation-based immunosuppressive agents for the better therapeutic effect for post-LR HCC recurrence.

Despite all these challenges, we’re convinced more monitoring and treatment strategies for the prevention of recurrence in high-risk patients with HCC would occur. Critically, post-surgical monitoring of recurrence is an indispensable follow-up element in order to yield favorable prognosis of patients with HCC. Models incorporated by the high-risk recurrent variables including DNA methylation markers could estimate the probability of tumor relapse after LR. This study allows for a more accurate stratification of patients receiving LR and strict recurrence monitor after sugery, and also need to validate the data in large sample size applied in randomized controlled trials.