Histological transformation to small cell lung cancer (SCLC), particularly from EGFR mutant lung adenocarcinoma (LUAD), has been recognized as a mechanism of EGFR tyrosine kinase inhibitors (EGFR TKIs) resistance as listed in the NCCN (National Comprehensive Cancer Network) clinical practice guidelines for non-small cell lung cancer (NSCLC) (https://www.nccn.org/, 2021.V3) [1, 2]. The gene discussed is EGFR; the disease is lung adenocarcinoma.