PDCD1 and small cell lung carcinoma: Although tumor PD‐L1 expression is a potential predictive marker of clinical response to anti‐PD‐1/PD‐L1 therapy, little is known about its association with clinicopathological features, including prognosis, in high‐grade neuroendocrine tumors (HGNETs), including small‐cell lung carcinoma (SCLC) and large‐cell neuroendocrine carcinoma (LCNEC), of the lung.