FIGURE 1.

Flowchart of the systematic review of the literature throughout different phases. The literature search was performed from July 1, 1980, to June 30, 2020. PubMed/Medline, EMBASE, Scopus, Google Scholar, EMBASE, The Cochrane Library, Web of Science, International Clinical Trials Registry, Network Digital Library of Theses and Dissertations, Dissertations and Theses Global Databases were searched in addition to hand search of references of pertinent articles or books. Initially, a total of 179,908 titles were retrieved. During the first screening, 145,603 articles were excluded as their titles revealed that the respective articles did not fulfill the inclusion criteria. During the second screening, a total of 10,723 articles were excluded because found to be duplicate publications. By the third screening, 23,092 studies were excluded, and the remaining 165 articles were fully appraised. A total of 150 studies were excluded as they did not report postoperative patient survival (n = 73), they included patients undergoing multiple interventions (n = 65), they included patients with tumors that were not hepatocellular carcinomas (n = 9), or the hazard ratios were not reported or there was not enough data to estimate the hazard ratios (n = 3). Overall, the total number of studies that were included in this meta-analysis was 15.