Genome sequencing identified TP53 and RB1 loss-of-function mutations in the vast majority of SCLC cases but failed to identify additional recurrent mutations to classify SCLC subtypes, with the overall genomic landscape characterized by extensive heterogeneity (George et al., 2015; Peifer et al., 2012; Rudin et al., 2012). This evidence concerns the gene RB1 and small cell lung carcinoma.