Endobronchial ultrasound‐guided re‐biopsy of non–small cell lung cancer with acquired resistance after EGFR tyrosine kinase inhibitor treatment

BACKGROUND: Few studies assessed the use of endobronchial ultrasound (EBUS)‐guided re‐biopsy for detecting the T790M mutation after epidermal growth factor receptor‐tyrosine kinase inhibitor (EGFR‐TKI) failure. METHODS: A total of 2996 EBUS procedures were performed during the study period (January 2019–June 2022). In total, 44 consecutive patients who underwent EBUS‐guided re‐biopsy (56 procedures) for detecting the T790M mutation were analyzed. The success rates and T790M mutation frequencies were analyzed according to the re‐biopsy site and EBUS method. Multivariate logistic regression analyses were used to identify factors affecting the likelihood of the T790M mutation. RESULTS: The success rates for the mutation analyses using EBUS with a guide‐sheath (EBUS‐GS), EBUS guided transbronchial needle aspiration (EBUS‐TBNA), and EBUS‐GS with EBUS‐TBNA for re‐biopsy were 80.6% (29/36), 93.3% (14/15), and 100% (5/5), respectively. Patients who underwent lymph node biopsy using EBUS‐TBNA had an increased rates of the T790M mutation compared with those undergoing lung biopsy using EBUS‐GS (EBUS‐TBNA, 60.0%; EBUS‐GS with EBUS‐TBNA, 40.0%; EBUS‐GS, 11.1%; p < 0.001). In multivariate analysis, the use of a first‐generation EGFR‐TKI (odds ratio [OR], 4.29; 95% confidence interval [CI], 1.05–17.58; p = 0.043) was associated with occurrence of the T790M mutation. Re‐biopsy of the metastatic site tended to be associated with a higher T790M mutation rate. Mild hemoptysis occurred in 3.6% (2/56) of the patients. CONCLUSIONS: EBUS‐guided re‐biopsy can be used for detecting the T790M mutation in patients who failed EGFR‐TKI therapy. The T790M mutation frequency differed according to the re‐biopsy site. The use of a first‐generation EGFR‐TKI was an independent predictor of the T790M mutation.