EGFR and small cell lung carcinoma: In fact, in a sizable percentage of lung cancer cases (10–14% cases), resistance to EGFR agents is linked to a lineage-switching phenomenon, which encompasses trans-formation of adenocarcinoma of the lung (LUAD) to squamous cell carcinoma (SCC) or small cell lung cancer (SCLC), correlating with additional mutations in p53 and Rb1.