CD274 and medical procedure: Previous results on PD-L1 expression in lung NEN vary considerably: Fan et al. reported PD-L1 positivity in as much as 58.8% of 80 lung NEN patients (37), and Tsuruoka et al. (n = 227) detected PD-L1 expressed in 10.4% of large cell and 5.8% of small cell NEC (42).