RB1 and small cell lung carcinoma: A causal role for RB1 is further supported by the observation that patients who present with EGFR/TP53/RB1 triple mutant lung cancers (approximately 5% of all EGFR-mutant cases) are at a sixfold higher risk for SCLC transformation compared to patients with EGFR-mutant lung cancer who do not harbor concurrent alterations in TP53 and RB1 (Offin et al., 2019).