Abstract
Background. A small number of patients with non-small cell lung cancer (NSCLC) simultaneously have activating epidermal growth factor receptor (EGFR) mutations and EGFR-tyrosine kinase inhibitor (TKI) resistance mutations (T790M) before gefitinib therapy. During a 3-year period between January 2008 and December 2011, 146 of the 503 NSCLC patients at our hospital had activating EGFR mutations. It is noteworthy that 3 harbored both activating EGFR mutations and T790M simultaneously. Cases. Case 1: A 70-year-old man. Adenocarcinoma was diagnosed with transbronchial biopsy [cT2aN2M1b (OSS, BRA), stage IV]. Both L858R and T790M mutations were detected simultaneously with the PCR-Invader assay. He was given gefitinib as 2nd-line chemotherapy, but treatment was discontinued due to regrowth of the primary tumor. Case 2: An 81-year-old man. Adenocarcinoma was diagnosed from bronchial brushing cytology, and right lower lobe lobectomy was performed [pT1N0M0, stage I]. Multiple pulmonary metastases were identified after surgery, while L858R, G719S, and T790M mutations were detected simultaneously in the resected lung tumor. He was given gefitinib therapy and a partial response was achieved. Case 3: An 80-year-old man. Adenocarcinoma was diagnosed with bronchial curettage [cT2bN3M0, stage IIIB]. Both exon 19 deletion and T790M mutation were detected simultaneously. We performed thoracic radiotherapy. After regrowth of the primary tumor and multiple pulmonary metastases were identified. He was given gefitinib, and a partial response was achieved. Conclusion. A small number of patients have both activating EGFR and T790M mutations. Response to EGFR-TKI therapy varies from case to case.
