In SCLC, TP53 and retinoblastoma susceptibility gene (RB1) inactivation are the most common molecular alterations, of which TP53 and RB1 mutation rates range between 45–90% and 23.8–67% [4,5,6], respectively, suggesting that TP53 and RB1 mutations play an important role in the carcinogenesis of SCLC. The gene discussed is RB1; the disease is small cell lung carcinoma.