Besides NE differentiation, SCLC is further distinguished from other major NSCLC subtypes such as lung adenocarcinoma (LUAD) and squamous cell carcinoma by its unique cellular morphology (Rudin et al., 2019) and genetic hallmarks including frequent inactivation of tumor suppressors TP53 and RB1 (Peifer et al., 2012; George et al., 2015). This evidence concerns the gene RB1 and small cell lung carcinoma.