Feasibility of re‐biopsy and EGFR mutation analysis in patients with non‐small cell lung cancer

BACKGROUND: In cases of EGFR‐tyrosine kinase inhibitor (TKI) failure, re‐biopsy may be useful to understand resistance mechanisms and guide further treatment decisions. However, performing re‐biopsy is challenging because of several hurdles. We assessed the feasibility of re‐biopsy in advanced non‐small cell lung cancer (NSCLC) patients in real‐world clinical practice. METHODS: We retrospectively reviewed the clinical and pathologic data of advanced NSCLC patients who experienced disease progression after previous treatment with EGFR‐TKIs at a single tertiary hospital in Korea between January 2014 and December 2016. Re‐biopsy specimens included small biopsy, surgical tissue, or liquid‐based cytology. EGFR mutation was tested using peptide nucleic acid‐mediated clamping PCR. RESULTS: Of the 230 NSCLC patients that experienced progression after EGFR‐TKI therapy, 105 (45.7%) underwent re‐biopsy. Re‐biopsy was successfully performed in 94 (89.5%) patients, and 11 patients were diagnosed with no malignancy. The complication rate was 8.6%, including seven cases of pneumothorax. EGFR mutation testing was performed on 75 patients using re‐biopsy specimens. Of the 57 patients who had sensitizing mutations at diagnosis, T790M mutations were found in 19 (33.3%), while 38 (66.7%) had no T790M mutation. Multivariate analysis showed that the re‐biopsy group was younger (P = 0.002) and exhibited a previous response to EGFR‐TKIs (P < 0.001). CONCLUSION: Re‐biopsy in advanced NSCLC is feasible in real world clinical practice, particularly in younger patients and those who achieved a previous response to EGFR‐TKIs.