Objective  To investigate the clinical value of the Super-ARMS assay in detecting epidermal growth factor receptor (EGFR) T790M mutations in circulating tumor DNA (ctDNA) in plasma samples of lung cancer patients in real-world settings.

  Methods  A total of 307 patients with lung cancer diagnosed in Beijing Chest Hospital from January 2019 to June 2020 were enrolled. EGFR mutations in tumor tissues were detected by the amplification refractory mutation system (ARMS), and EGFR mutations in plasma were detected by the Super-ARMS assay. The progression-free survival (PFS) of patients with EGFR T790M mutations was compared according to the samples using different methods of detection; survival analysis was performed for this purpose.

  Results  Of the 307 patients, 153 underwent re-biopsy for disease progression. EGFR T790M mutations were detected in 34 of 74 (45.9%) patients after tissue re-biopsy. EGFR T790M gene mutations in plasma ctDNA were detected in 51 of 141 (36.2%) patients. Kaplan–Meier survival analysis showed that there was no significant difference in the median PFS of tissue EGFR T790M mutation-positive and plasma EGFR T790M mutation-positive patients who received third-generation of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) (16.3 vs. 11.4 months, x²=1.138, P>0.05). There was no significant difference in the median PFS of tissue EGFR T790M mutation-negative and plasma EGFR T790M mutation-negative patients who did not receive third-generation EGFR-TKIs (7.0 vs. 7.0 months, x²=0.47, P>0.05).

  Conclusions  The application of Super-ARMS-based detection of EGFR T790M mutations using peripheral blood samples is promising; plasma samples can replace tissue samples to a certain extent for the detection of EGFR T790M mutations and for predicting the efficacy of third-generation EGFR-TKIs.