2016 Volume 56 Issue 5 Pages 331-336
Objective and Method. We examined the changes in the EGFR mutation status, including the frequency of acquired T790M mutations, in 25 non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations who underwent a re-biopsy (include pleural effusion) from January 2013 to March 2015. Results. The male:female ratio was 7/18, at the time of the initial chemotherapy the median age was 67 years (range, 33-77), the types of EGFR mutation included exon19 del (n=12), L858R (n=11), L858R+T790M (n=1), and T751-I759 del ins N (n=1). Eighteen patients were treated with gefitinib as first-line treatment, and 12 patients underwent a re-biopsy just before the administration of a second-line treatment. The biopsy sites at the initial examination were the primary lung tumor (n=21), pleural dissemination (n=1), the bone (n=2), and pleural effusion (n=1). The biopsy site at re-biopsy was the primary tumor (n=9), pleural effusion (n=15), and the lymph nodes (n=1). At re-biopsy, 10 patients (40%) had acquired the T790M mutation. In four cases that received a biopsy using a bronchoscope, the results between the specimen and a mutation analysis were discordant. Conclusion. The presence of a resistance gene affects the choice of subsequent treatment. However, the ability to perform a genetic analysis using biopsied tissue samples is limited. We should therefore consider the use of cytology specimens, including fluid samples.
