Yuan C, Jiang H, Jiang W, et al. - Diversity in EGFR (epidermal growth factor receptor) mutation status was evident in metastatic non-small cell lung cancer (NSCLC) patients undergoing the first- and second-generation tyrosine kinase inhibitors (TKIs) following disease progression. It is crucial to monitor EGFR mutation changes in order to make subsequent clinical decisions as well as to explore the underlying mechanisms of acquired resistance.

• A retrospective analysis of metastatic NSCLC patients harboring EGFR mutation.

• Samples were obtained prior to treatment as well as at the time of disease progression following first-line EGFR-TKIs therapy.

• In the same and different simple types, the inconsistency rate of EGFR mutations was 72.22% (26/36) and 92.31% (48/52), respectively.

• Four groups named Group A, B, C, and D were defined based on alterations in terms of EGFR mutations.

• EGFR-sensitive mutation negative and T790M negative (39.77%) comprised Group A and EGFR-sensitive mutation positive and T790M negative (18.19%) was Group B.

• Group C was defined as EGFR-sensitive mutation negative and T790M positive (36.36%) and Group D comprised EGFR-sensitive mutation positive and T790M positive (5.68%).

• No statistically significant differences were found in ORR and DCR between the four groups.

• Group A, B, C, and D showed PFS of 12.26, 7.96, 10.55, and 13.81 months, respectively, with statistical significance.