Utility of serum DNA and pyrosequencing for the detection of EGFR mutations in non-small cell lung cancer

Mutations in the EGFR gene are critical determinants of treatment with EGFR tyrosine kinase inhibitors (TKIs) for non-small cell lung cancer (NSCLC) patients. DNA isolation from tumor samples usually requires surgery; therefore, we wanted to isolate DNA from circulating tumor cells by using the serum of NSCLC patients. This protocol was recently published. DNA was isolated from the serum of 52 Turkish NSCLC patients and their EGFR mutation status was examined by pyrosequencing. EGFR mutations were detected in 25 of the 52 patients (48.1%): 17 patients with delE746-A750, 2 with delE747-A750insP, and 6 with L858R. All mutations detected by pyrosequencing were confirmed by dideoxy sequencing, and the presence of the same mutations in the tumors was verified by using paraffin embedded tissues of all the patients. Mutations were detected more frequently in adenocarcinomas (24 of 36, 66.7%) than in squamous cell carcinomas (1 of 16, 6.3%) (P < 0.001). These results confirm the utility of serum DNA and pyrosequencing for the detection of EGFR mutations in patients with advanced NSCLC.