Studies suggest that the prognostic significance of TC PD-L1 expression in oral cancer depends on the specificity of tumor site (50); PD-L1 upregulation in tongue squamous cell carcinoma (TSCC) is associated with a higher recurrence rate after tongue cancer surgery (51), later TNM staging and shorter PFS (52); but it was not correlated with OS (53). This evidence concerns the gene CD274 and lip and oral cavity carcinoma.