Chemotherapy influence EGFR mutation status for Chinese patients with regionally advanced non-small cell lung cancer.

7031 Background: EGFR-TKI has been recommended as standard second-line therapy for advanced non-small cell lung cancer (NSCLC) in China. However, it remains unclear whether there is a need to detect EGFR mutations before using second-line EGFR-TKI therapy. The key to answer this question is to identify whether chemotherapy may change EGFR mutation status. Methods: Total of 61 (stage IIb–IIIa) NSCLC pts were included in this study. All patients received neoadjuvant chemotherapy 2-4 cycles before surgery. The surgical specimen were microdissected before detection. EGFR mutation were detected by denaturing high performance liquid chromatograph (DHPLC) in tumor samples from both pre- and post- neoadjuvant chemotherapy. Results: The EGFR mutation ratio in all pts are 41.0% (25/61) before chemotherapy and dropped to 29.5% (18/61) after chemotherapy. 46 pts remained the same EGFR status after chemotherapy (including 32 cases of wild-type and 14 cases of mutant-type), 24.6% pts (15/61) were discordant for EGFR mu...