PDCD1LG2 and hepatocellular carcinoma: Subgroup analyses regarding cancer type clarified that high PD-L2 expression had a unfavorable prognostic value for OS in patients with HCC (HR = 1.60, 95% CI = 1.12–2.29, P = 0.011), while no significant association was observed in RCC, esophageal cancer or gastric cancer (OS for RCC: HR = 1.86, 95% CI = 0.55–6.27, P = 0.315; esophageal cancer: HR = 0.91, 95% CI = 0.60–1.38, P = 0.647; gastric cancer: HR = 1.33, 95% CI = 0.81–2.17).