The meta-analysis revealed that the proteins related to tumor progression, PD-L1, Mdm2, and Mucin-4 were significantly associated with greater abundance in OSCC patients, with an Odds Ratio (OR) of 0.12 (95% CI: 0.04–0.40), 0.44 (95% CI: 0.24–0.81), and 0.18 (95% CI: 0.04–0.86), respectively, with a moderate certainty of evidence. Here, CD274 is linked to neoplasm.