CD274 and neuroendocrine carcinoma: The positive PD-L1 expression percentages in digestive system NEC tumor cells were reported previously as 28.6% (6/21) (23), 14% (5/37) (24), 37.5% (6/16) (25), 100% (9/9) (26), and 41.17% (7/17) (27), although the primary site constitutions were different in these studies.