EGFR mutation detection

Specimens used for EGFR mutation detection were obtained by surgery, fine-needle small biopsy guided by ultrasound or computed tomography, transbronchial biopsy, or malignant effusion cell blocks. Polymerase chain reaction (PCR) testing and next generation sequencing (NGS, 68 genes, Table S1) were used for EGFR mutation detection in this study. PCR can only detect specific mutations and cannot fully reflect the concomitant mutations. The kit for PCR was provided by Amoy Diagnostics Co., Ltd. (AmoyDx). Most patients diagnosed in 2017 used PCR testing. However, NGS can sequence gene mutations in the entire genome, and we used it for some analysis in this study.