Abstract:Objective To explore and analyze the actual use of different detection methods and samples in detection of epidermal growth factor receptor (EGFR) mutation in patients with advanced lung adenocarcinoma. Methods The clinical data of 170 patients with advanced lung adenocarcinoma receiving EGFR gene detection in Department of Respiratory Medicine of Nanjing Chest Hospital were collected and an analysis of initial result and continuous detection conditions was made. Results The EGFR sensitive mutation rate of the first detection in 170 patients was 49.4% (84/170). The detection rate of EGFR sensitive mutation in female patients was higher than that in male patients ［61.4% (43/70) vs. 41.0% (41/100); χ2=6.875, P=0.009］. The detection rate of EGFR sensitive mutation in patients aged 65 or older was lower than that in patients younger than 65 years old ［41.6% (47/113) vs. 64.9% (37/57); χ2=8.242, P=0.004］. The detection rate of EGFR sensitive mutation in smokers was lower than that in nonsmokers ［34.3% (24/70) vs. 60.0% (60/100); χ2=10.892, P=0.001］. A total of 60 patients were retested after disease progression, and the detection rate of T790M was 48.3% (29/60). The detection rate of EGFR sensitive mutation in the initial examination in 170 patients: tumor tissue (biopsy and pleural effusion cell wax block) for 50.8% (64/126), ctDNA (pleural effusion and peripheral blood) for 45.5% (20/44), with no significant difference (χ2=0.372, P=0.542); PCR method for 51.0% (77/151), nextgeneratio sequencing (NGS) method for 36.8% (7/19), with no significant difference (χ2=1.352, P=0.245). The detection rate of T790M in 60 patients receiving drug resistance: PCR method for 51.9% (14/27), NGS method for 45.5% (15/33), with no significant difference (χ2=0.243, P=0.622). The use of tumor tissue was 74.1% (126/170) in the initial examination, and ctDNA accounted for 25.9% (44/170). The use of tumor tissue was 11.7% (7/60) in the second examination, and ctDNA accounted for 88.3% (53/60). The use of tumor tissue was 23.1% (3/13) in the third examination, and ctDNA accounted for 76.9% (10/13). The proportions of detection methods used for the 3 tests were as follows, the first test: PCR accounted for 88.8% (151/170), and NGS accounted for 11.2% (19/170); the second test: PCR accounted for 45.0% (27/60), and NGS accounted for 55.0% (33/60); the third test: NGS accounted for 100% (13/13). Conclusion For patients with advanced lung adenocarcinoma, making full use of different tumor specimens and ctDNA helps improving the detection rate of EGFR mutation, and reasonable use of PCR technology and NGS method can bring maximum benefits to patients.

Key words:Lung neoplasms,Adenocarcinoma,Receptor, epidermal growth factor,Mutation,Laboratory techniques and procedures