Liquid biopsy by combining 5-hydroxymethylcytosine signatures of plasma cell-free DNA and protein biomarkers for diagnosis and prognosis of hepatocellular carcinoma

•A novel liquid biopsy approach was developed for HCC diagnosis, prognosis, and surveillance.•Novel HCC score defined here showed excellent capacity in distinguishing HCC patients from liver cirrhosis patients.•HCC score could predict the early recurrence risk for HCC patients after receiving surgical operation.•HCC score could sensitively monitor tumor burden and progression of HCC in longitudinal.