EGFR DNA Extraction and Sequencing

The DNA extraction and sequencing process of EGFR was done according to previous experience [17 (link)]. Briefly, tumor tissue from frozen specimen was collected to extract the DNA via the application of QIAamp DNA Kit (Qiagen, Valencia, CA, USA) according to the manufacturer’s guide document. After the DNA genome was obtained, categories of EGFR, including the wild-type and mutation phenotype, were amplified and detected via the use of real-time polymerase chain reaction (PCR). After that, the DNA sequencing reaction was conducted by ABI PRISM 3130XL System (Applied Biosystems, Foster City, CA, USA). Two types of EGFR genomes were categorized after the above procedures: the EGFR wild-type and EGFR mutation type. To be more specific, EGFR mutation that was analyzed in the current study included phenotypes of both the L858R expression as well as Exon 19 in-frame deletion.