Anar, CeydaKömürcüoğlu, BernaPolat, GülruBüyükşirin, MelihBatum, ÖzgürErdoğan, Kadri MuratGüldaval, Filiz2023-03-222023-03-2220212147-0758https://hdl.handle.net/20.500.14034/1047https://doi.org/10.5505/KTD.2021.82856https://search.trdizin.gov.tr/yayin/detay/517063INTRODUCTION: To compare patient characteristics between the T790M-positive and T790M-negative populations, and to analyze the post-progression survival (PPS) after initial tyrosine kinase inhibitor (TKI) failure in order to investigate the prognosis in patients undergoing rebiopsy. METHODS: We investigated the patient characteristics, including the initial EGFR-TKI response and T790M status at the time of rebiopsy or liquid biopsy, subsequent treatment after resistance to the initial EGFR-TKI (the presence of EGFR-TKI re-challenge), treatment just before biopsy and/or rebiopsy (EGFR-TKIs or chemotherapy), the timing of the rebiopsy (just after the initial EGFR-TKI failure or others). RESULTS: No difference was found between the two groups with T790M mutation positive and negative in terms of age, gender, and metastasis location. Only patients with positive T790M mutation had higher progression after TKI use compared to negative ones (p: 0.000). The progression-free median survival in patients using TKI was 19.33 months in the group with T790M mutation and 22.25 months in the negative group. Overall survival was found to be 75 months and 27.5 months in the T790M positive and negative group, respectively, and this was statistically significant. (p: 0.009). DISCUSSION AND CONCLUSION: Overall survival was significantly longer in the T790M positive group than in the T790M negative group. In addition, liquid biopsy can be performed several times for patients with progression after EGFR-TKI use and who do not want to undergo tissue biopsyeninfo:eu-repo/semantics/openAccessArticle10.5505/KTD.2021.828561025156517063