RB1 and small cell lung carcinoma: In SCLC, TP53 mutations are reported in 86–93% and RB1 mutations in 40–62% (Peifer et al. 2012, Dowlati et al. 2016, Miyoshi et al. 2017, Eskander et al. 2020) while biallelic inactivation of TP53 and RB1 (by any mechanism) is a universal finding for all SCLC (George et al. 2015).