부산대학교 도서관

Background. Non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutation responds to EGFR tyrosine kinase inhibitor (TKI) treatment well; however, it subsequently develops resistance to these drugs. Several mechanisms underlying the development of resistance to EGFR-TKI have been reported. Although transformation to small cell lung cancer (SCLC) accounts for 2-15% of such cases, little is known about treatments or clinical outcomes. Case 1. A 66-year-old woman with EGFR-mutated NSCLC was observed to have pleural effusion and dissemination during the administration of osimertinib. Transformation to SCLC was found in the pathological cell block examination of pleural effusion. Case 2. A 47-year-old man with EGFR-mutated NSCLC was found to have elevated tumor marker levels (NSE and ProGRP) and progressive pleural dissemination during S-1 treatment. Transformation to SCLC was detected in the pathological examination of pleural dissemination. Case 3. A 67-year-old man with EGFR-mutated NSCLC was found to have enlargement of his primary tumor. Transformation to SCLC was observed in the rebiopsy specimen of the primary tumor. All three patients received cisplatin and irinotecan, and their disease was controlled after transformation to SCLC. Conclusion. Cisplatin and irinotecan may be potential treatments for patients with EGFR-mutated NSCLC after transformation to SCLC. However, the accumulation of cases is required as there are few detailed reports on this treatment.