Prognostic and clinicopathological significance of PD-1 expression in hepatocellular carcinoma: a meta-analysis

Objective We performed a meta-analysis to evaluate the prognostic and clinicopathological significance of programmed cell death-1 (PD-1) expression in patients with hepatocellular carcinoma (HCC). Methods We searched the Wanfang, Chinese Biomedical Literature, CNKI, PubMed, Embase, and Web of Science databases for relevant articles from inception to 1 July 2020. Statistical analysis was performed using RevMan 5.3 (Cochrane, London, UK) and Stata 14.0 software (StataCorp LP, College Station, TX, USA). Results Eight studies involving 732 patients with HCC were included. Higher expression of PD-1 predicted longer disease-free survival [hazard ratio (HR) 0.53, 95% confidence interval (CI): 0.38-0.72]. No significant correlation was observed between PD-1 expression and overall survival (HR 0.89, 95% CI: 0.58-1.35). PD-1 expression was correlated with age [odds ratio (OR) 0.66, 95% CI: 0.46-0.94] and alpha-fetoprotein level (OR 2.27, 95% CI: 1.45-3.55); no correlation was observed with sex, tumor size, tumor metastasis, hepatitis B virus history, tumor stage, or tumor multiplicity. Sensitivity analysis demonstrated no excessive effect on stability of the pooled results. No significant publication bias was found among the identified studies. Conclusion PD-1 overexpression predicted better disease-free survival in patients with HCC. Moreover, PD-1 expression was associated with age and alpha-fetoprotein level.