CD274 and squamous cell carcinoma: Most of the adequate cell yields in squamous cell carcinoma cases had no PD-L1 expression (PD-L1 < 1%) (51.8%), whereas 27.3% had low expression (PD-L1 1–49%) and 20.9% had high PD-L1 expression (PD-L1 ≥ 50%) (p = 0.003).