Clinicopathological and Prognostic Roles of the Expression Levels of the Programmed Cell Death-1 Gene in Patients with Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis.

Multiple studies have explored the prognostic role and clinical significance of the expression of the programmed cell death-1 () gene in hepatocellular carcinoma (HCC). However, the results have been inconsistent. This study evaluated expression and its clinical significance in patients with HCC, as well as the correlation between HCC pathological features and prognoses. All related research in PubMed, Embase, and Web of Science prior to October 31, 2019, was retrieved. The Newcastle-Ottawa Scale was used to evaluate the quality of the literature. Stata 14.0 statistical software was used to analyze the data, and the correlations between expression and the clinicopathological characteristics of patients were analyzed using the odds ratio (OR) and its 95% confidence interval (CI). The hazard ratio (HR) and its 95% CI were used to analyze the correlation between high expression and patient prognosis. Begg's test was used to evaluate publication bias. A total of 581 patients were analyzed in the six studies included in the meta-analysis. Pooled analysis revealed that high levels of expression did not correlate with overall survival (HR = 0.79; 95% CI: [0.41-1.54];  = 0.493). PD-1 positivity was associated with better disease-free survival (HR = 0.52; 95% CI: [0.38-0.72];  < 0.0001). Furthermore, elevated expression corrected for age (OR = 0.62, 95% CI: [0.41-0.96];  = 0.030) and alpha-fetoprotein levels (OR = 2.27, 95% CI: [1.46-3.55];  < 0.0001), were not correlated with patient sex, tumor size, tumor multiplicity, hepatitis B virus history, tumor node metastasis stage or Barcelona Clinic Liver Cancer stage. This meta-analysis revealed that expression may be a useful prognostic marker in HCC patients. Prospective clinical studies are needed to support these findings.