Chemotherapy On T790M Mutation Status In Patients With Advanced NSCLC After EGFR-TKI Resistance

Objective : Detecting patients with advanced NSCLC EGFR-TKI resistant front after chemotherapy, peripheral blood EGFR exon 20 T790 M mutation status, investigate the effect of chemotherapy in patients with advanced NSCLC after EGFR-TKI resistant T790 M mutation status.Methods: Press QIAamp Blood Mini Kit kit extract serum free DNA, using the ARMS method in peripheral blood plasma DNA in EGFR exon 20 T790 M mutation detection. And to analyze its clinical features, efficacy and progression-free survival and time relationships.Results:1.34 cases of acquired resistance to patients before receiving chemotherapy serum DNA sample test results showed that patients T790 M mutation rate was 29.4%(10/34) after chemotherapy serum DNA sample test results showed that patients T790 M mutation rate was 5.9%(2 / 34), a significant difference(P = 0.023).2. T790 M mutation-positive NSCLC patients with advanced age, gender, smoking, clinical stage, ECOG score, initially EGFR mutation and EGFR-TKI types of drugs are nothing but the EGFR-TKI resistance to progress after the type, the difference statistics significance P = 0.023).3. Targeted drug therapy after chemotherapy in patients with the disease under control(PR + SD) in, T790 M mutation rate was 33.3%(8/24), higher than the disease progression(PD) were 20.0%(2/10), but the difference was not statistically significant(P=0.683). Disease control rate(DCR) T790 M T790M-negative patients was higher than positive patients(DCR, 54.2% vs 45.8%), but no significant difference( P = 0.785).4.The T790 M mutation-positive patients before chemotherapy PFS than the T790 M mutation-negative patients live longer(5.4 months vs 3.5 months,P=0.000), after chemotherapy T790 M mutation-positive patients with PFS was significantly shorter than the T790 M negative(3.2 months vs 4.2 months, P = 0.000).5.Cox Multivariate analysis showed that chemotherapy before T790 M mutation status of independent factors affecting the PFS(RR = 0.667,95% CI: 0.069-0.975, P = 0.034).Conclusion:1. Chemotherapy can affect the peripheral blood of advanced NSCLC patients with T790 M mutation status.2. Distant metastasis, before and after chemotherapy T790 M were negative and there were positive shorter PFS, these factors may prompt NSCLC patients with poor prognostic factors;3.Before chemotherapy T790 M mutation status were independent factors for PFS.