EGFR and small cell lung carcinoma: Phenotypic transformation to SCLC or SqCC and EMT with change to sarcomatoid phenotype are mechanisms of acquired resistance to EGFR-TKIs of all three generations that can occur in up to 15% of EGFRM+ LACs during TKI-treatment and are associated with rapid clinical course [17,18,29,30,192,193].