CD274 and squamous cell carcinoma: In another retrospective study by Vieira et al., positive PD-L1 (≥5%) staining was observed in tumor cells in 53.3% (40/75) of the cases by immunohistochemistry and the levels of PD-L1 were also higher in PSC than those in adenocarcinoma (25.0%, 5/20), squamous carcinoma (15.8%, 3/19), or large cell carcinoma (20.0%, 3/15) [69].