In this context, the present study was performed to investigate the detection rate of T790M by repeated rebiopsy, identify the clinical factors related to repeated rebiopsy, and assess survival outcomes according to the methods and number of repeated rebiopsies in patients with lung adenocarcinoma who received sequential osimertinib after failure of previous 1st or 2nd generation EGFR-TKIs. Here, EGFR is linked to lung adenocarcinoma.