VTCN1 and esophageal squamous cell carcinoma: The negative effect of elevated B7-H4 on OS was demonstrated in patients with esophageal squamous cell cancer (pooled HR = 1.96; 95% CI = 1.28–3.02; P = 0.002), gastric cancer (pooled HR = 1.74; 95% CI = 1.36–2.21; P < 0.001), pancreatic cancer (pooled HR = 2.40; 95% CI = 1.37–4.21; P = 0.002) and other cancers (pooled HR = 1.73; 95% CI = 1.41–2.11; P < 0.001).