CD8A and hepatocellular carcinoma: Previous studies found that CD8+ T cell played a critical role in immunotherapy and was correlated to prognosis in HCC (Mahmoud et al., 2011; Erdag et al., 2012; Danilova et al., 2016; Riaz et al., 2017; Xu et al., 2019; Orhan et al., 2020).