CD274 and oral cavity squamous cell carcinoma: In oral squamous cell carcinoma (OSCC), PD-L1 expression in more than 10% of TCs was associated with tumor recurrence and lower disease-specific survival (46), and when the PD-L1 staining threshold was not considered, PD-L1 expression was positively correlated with the tumor size (47), lymph node metastasis at diagnosis, and overall tumor-related death (48).