...60-year-old woman in our transformed SCLC cohort harbored EGFR 19 del mutant at allele frequency of 50.39%,she received osimertinib plus epirubicin/cyclophosphamide as 1st line treatment and reached partial response, with survival of 4 years to date....SCLC patients with EGFR mutation who transformed from lung adenocarcinoma may be potential benefit population using EGFR inhibitors.