A Rare Case of Small Cell Lung Cancer With an Epidermal Growth Factor Receptor Mutation and Its Response to Osimertinib

Small cell lung cancer (SCLC) accounts for less than 15% of the cases of lung cancer. Epidermal growth factor receptor (EGFR) mutations are rarely reported in association with SCLC. EGFR tyrosine kinase inhibitors (TKI) are approved as the first-line therapy for metastatic non-small cell lung cancer (NSCLC). The clinical effect of EGFR mutations and its response to osimertinib are unknown in SCLC. We report a case of EGFRpositive metastatic SCLC in a 63-year-old female who was treated with the third-generation TKI, osimertinib.