They identified two major and one minor subsets: SCC-like LCNEC, characterized by TP53 + RB1 co-mutation/loss and MYCL amplification; NSCLC-like LCNEC, characterized by the lack of co-altered TP53 + RB1 and almost universal occurrence of NSCLC-type mutations (STK11, KRAS and KEAP1); and carcinoid-like LCNEC, characterized by MEN1 mutations and low mutational burden. The gene discussed is RB1; the disease is carcinoid tumor.