In this study, investigators aim to find out how plasma 5hmC level changes in hepatocellular carcinoma patients after liver resection, and determine whether 5hmC can be used as a biomarker for HCC recurrence monitoring.

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and the third leading cause of cancer-related death worldwide. Liver resection is a common treatment for HCC. However, even after successful surgical resection, most patients suffered from recurrence or progression of the tumor. Because clinical staging systems cannot precisely predict the outcome of patients with HCC, it's of great interest to search biomarkers for HCC. Among them, alpha-fetoprotein (AFP) is the most well-studied. However, the applicability of AFP for HCC after surgical resection of tumor is still uncertain.

The discovery of cell-free DNA (cfDNA) originating from different tissues in the circulating blood has revolutionary potential for the clinic. Liquid biopsy-based biomarkers and detection tools offer substantial advantages over existing diagnostic and prognostic methods, including being minimally invasive. They thus have a cost-efficient potential to promote higher patient compliance and clinical convenience to enable dynamic monitoring.

5-hydroxymethylcytosine (5hmC) is the intermediate of active demethylation from 5-methylcytosine. 5hmC not only marks active demethylation but also serves as a relatively stable DNA mark that plays distinct epigenetic roles. Recent genome-wide sequencing maps of 5hmC in various mammalian cells and tissues support its role as a marker for gene expression. Previous studies have established 5hmC-Seal technology for 5hmC profiling in cfDNA and showed that the differentially enriched 5hmC regions in cfDNA are excellent markers for solid tumors.

In this study, investigators aim to find out how plasma 5hmC profile changes in hepatocellular carcinoma patients after liver resection, and determine whether 5hmC can be used as a biomarker for HCC recurrence monitoring.

Inclusion Criteria:

1. Patients who received liver resection within 3 months;
2. Hepatocellular carcinoma confirmed pathologically;
3. Serum alpha-fetoprotein level lower than 20ng/ml before hepatectomy.

Exclusion Criteria:

1. Patients with macroscopic tumor remnants;
2. Patients with other diseases which may affect the observation mentioned here;
3. Patients with medical history of other malignant tumors;
4. Pregnant or nursing women.

The population will be selected from patients who have received liver resection in the Liver Surgery Department of Zhongshan hospital.