Two studies classified LCNEC into 2 major subgroups: SCLC-like LCNEC patients were those with RB1 and TP53 mutations or copy-number loss, and NSCLC-like LCNEC patients had no co-alterations of RB1 + TP53 [15, 16]. This evidence concerns the gene RB1 and non-small cell lung carcinoma.