ALK and large cell neuroendocrine carcinoma: In this study, we investigated the prevalence of ALK alterations in a large cohort of neuroendocrine tumors of the lung, including LCNEC, SCLC, TC, and AC (n = 439) by immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and next-generation sequencing (NGS).