The investigators examined circulating tumor cells (CTC) in the perioperative peripheral blood of hundreds of HCC patients undergoing liver cancer surgery using CellSearch technology between 2013 and 2016. Although the investigators have done a preliminary study of the above data and published some results, the previous study was only a basic analysis. Now the investigators plan to carry out further in-depth analysis of these data, including hospitalization data, follow-up results, surgical tumors and blood specimens, and make full use of biostatistics, molecular biology, pathology and other related techniques to elucidate the association between the levels of CTC or CTC clusters and patients' disease during the perioperative period, and to explore the molecular basis of CTC production in hepatocellular carcinoma.