Study On The Effect Of Chemotherapy On EGFR Gene In Serum Of Patients With Advanced NSCLC

Objective:The aim of this study is to detect EGFR gene type at pre-chemotherapy and post chemotherapy,to evaluate the impact of platinum based chemotherapy for EGFR gene mutation, and provide theoretical foundation for clinical treatment.Methods:From November 2014 to June 2015, 40 cases serum DNA was collected in the first affiliated hospital of Shihezi University who was confirmed by pathology with stage III or IV lung adenocarcinoma. Serum DNA was collected before chemotherapy and after chemotherapy failed(or maintain stability after 6 months) from 3 ml venous blood to detect EGFR gene. All patients were given platinum based chemotherapy as first line treatment in hospital. Outcome was checked by lung CT after every two cycles. The standard was RECIST1.1 curative effect evaluation of therapeutic effect evaluation standard of solid tumor. The EGFR gene 19 and 21 exon was amplified by PCR and detected by direct sequencing before and after chemotherapy.Statistical processing: the data was analyzed by SPSS 17.0software, used Fisher test, P < 0.05 for statistically significant.Results: 1. In 40 patients, 38 cases was succeed for experiment, lost to follow-up in 1 case, DNA extraction failed in 1 case. In 38 patients who complete the test, 25 cases was male and 13 cases was female;20 cases have a smoking history and 18 cases were not.Before chemotherapy, patients with tissue EGFR gene mutation rate was 44.7%, 64.7% was with 21 exon mutations. Smoking patients EGFR gene mutation rate was 20.0%, non-smoking patients was 72.2%, non-smoking patients gene mutation probability was higher than smoking patients, the result was significant difference(P = 0.008).2. Before chemotherapy, tissue EGFR gene mutation was detected of 17 cases(44.74%), serum EGFR gene mutation was detected in 13 cases(34.3%), false negative proportion was 16%, the specificity was 100%,the sensitivity was 84% and Kappa value was 0.782(Kappa > 0.75).3. After chemotherapy the EGFR gene mutation rate was 50%(19/38) in serum, the main mutation was exon 21 by 73.7%(14/19).12 cases were positive for patients before and after chemotherapy, both before and after chemotherapy for 14 patients with negative, consistent mutation rate was 68.4%(26/38); 5patients from positive to negative, 7 patients from negative to positive. Before and after chemotherapy EGFR mutation in general was no statistically significant difference(P = 0.165).4.All 38 patients were accepted platinum based chemotherapy, CR 0 cases, PR 6 cases, SD 21 cases, PD 11 cases, disease control rate was 71.1%.The efficacy of chemotherapy in patients with EGFR gene mutation type is better than that of wild-type(P = 0.01).5.T790 M mutation of EGFR gene 20 exon was not detected.Conclusion: 1.Platinum based chemotherapy can change serum EGFR gene type in some advanced lung adenocarcinoma. 2.Some patients can benefited from another EGFR gene detection after chemotherapy.3.Blood EGFR gene detection can better reflects the EGFR gene status of advanced NSCLC patients.