Research Advancement on EGFR Mutation Detection of Cell-free DNA and Tumor Cell in Peripheral Blood of Patients with Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer. Epideral growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are the most important treatments currently for advanced NSCLC patients harboring activating EGFR gene mutations, and achieve significant clinical efficacy. T790M mutation occurs in half of NSCLC patents with acquired EGFR-TKI resistance. Screening for EGFR gene mutations in histological and/or circulating tumor cell or DNA samples of NSCLC patients can identify patients who would have a response to EGFR-TKIs or acquire resistance during the treatment. Quantitative analysis of plasma EGFR mutation is of great importance not only in early diagnosis of tumors, but also in curative effect evaluation and for follow-up. However, a strict requirement is proposed on the detection technique because of low DNA content and the fragmentation of the genes. To date, many methods have been applied to detect cfDNA EGFR mutations, including sequencing, real-time PCR (RT-PCR), amplification refractory mutation system (ARMS), mutant-enriched PCR (ME-PCR), denaturing high-performance liquid chromatography (DHPLC), digital PCR, and droplet digital PCR (ddPCR). However, of all the methods above, ddPCR has the highest sensitivity, allows high throughput operation. In conclusion, the ddPCR has a lot of future promise in clinical gene diagnosis.