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e13121 Background: Lung cancer patients with mutations in the epidermal growth factor receptor (EGFR) are primary candidates for EGFR-targeted therapy. Reliable analyses of such mutations have previously been possible only in tumor tissue. Here, we demonstrate that mutations can be detected in plasma samples of non-small cell lung cancer patients at Bach Mai Hospital and relation of different variables to the frequency of EGFR mutations. Methods: 193 patients with non-small cell lung cancer were identified with EGFR mutation by cobas EGFR Mutation Test v2 kit (Roche Diagnostics, USA), evaluating the EGFR mutation status with different variables. Results: The EGFR mutation rate was 43%, common in patients with adenocarcinoma, female, non-smoking, late stage disease. The rate of EGFR T790M mutation was 36.1%. Among 78 patients who was previous treated TKIs, EGFR mutation rate was 73.1% and the rate of EGFR T790M mutation was 50.8% at the time of progression. The concordance of EGFR mutation from plasma sample with tissue sample was 81%. Conclusions: EGFR mutation in plasma sample results was not different from those in tissue samples and similar with result of studies in Vietnam and worldwide.

e13120 Background: To determine the epidermal growth factor receptor ( EGFR) mutation status in non-small cell lung cancer (NSCLC) patients in Vietnamese population at Bach Mai Hospital, and relation of different variables to the frequency of EGFR mutations. Methods: The EGFR mutation status of 1451 tissue samples in NSCLC patients and correlation among different variables of age, gender, smoking habit and histology groups were evaluated. Results: A total of EGFR mutation analysis was performed, with an overall mutation rate of 40.7%. The most prevalent categories were in-frame deletions in exon 19 (57.2% of the overall mutations); followed by L858R and L861Q in exon 21 (35.7%); exon 18 (4,6%); double mutation: 2.9%; The T790M mutation in exon 20 represented approximately 2.5%; The pooled prevalence of EGFR mutation was higher in female (60.6%), non-smokers (61.1%), and patients with adenocarcinoma (42.2%). Conclusions: The prevalence of EGFR mutations of NSCLC in Vietnam is higher than that in the West, but comparably equal to that in some Asian countries. It is associated with female sex, non-smoker status, and adenocarcinoma, sample tissue type and age, but not depends on disease stage and tumor sampling.