RB1 and small cell lung carcinoma: Taken together the above-mentioned results provide evidence for TP53 and RB1 inactivation as predisposing factor for SCLC-transformation of EGFRM+ LACs and suggest that evaluating the mutational status of TP53 and RB1 at baseline might aid in foreseeing which LACs are more prone to SCLC-transformation following EGFR-TKI therapy [195,197,200].