Strikingly, programmed cell death-ligand 1 (PD-L1) and programmed cell death-1 (PD-1) were predominantly expressed in squamous cell carcinoma components (SCCCs) versus adenocarcinoma components (ACCs), where enhanced CD4+ FOXP3+ regulatory T cell and attenuated CD57+ natural killer cell infiltration were present, consistent with a landscape of fewer innate immune cells, more immunosuppressive cells. This evidence concerns the gene PDCD1 and squamous cell carcinoma.