A multicenter study of central nervous system (CNS) metastasis in EGFR-mutated advanced non–small-cell lung cancer in Thailand: CNS progression-free survival analysis.
Authors: Supavavej Archara , Chayangsu Chawalit , Benjawongsathien Duangnapa , Chantharakhit Chaichana , Sukaraphat Napawan , Neesanun Sunee , Paul Vinai , Sukauichai Sitthi , Bowornkitiwong Thipawan 
Published: June 2023

e14002 Background: Central Nervous System (CNS) metastasis is common in patients with advanced stage non-small cell lung cancer (NSCLC), which impacts their survival and quality of life. Nearly Half of NSCLCs in Thailand are EGFR (Epidermal Growth Factor Receptor) mutated NSCLCs. The aim of this study was to define the prevalence of CNS metastasis in EGFR mutated advanced NSCLC in Thai patients and their survival during the year 2013-2019.Now we reported CNS progression free survival data in subgroup with evidence of CNS progression. Methods: We retrospectively conducted a multicenter study of EGFR mutated advanced NSCLC from 9 government hospitals in Thailand from January 2013 to December2019. Demographic data and cancer treatments were recorded with previous reports of overall survival data in all cohorts. Brain imaging was performed upon neurologic signs and symptoms. Treatment of CNS metastasis, CNS progression date and overall survival data were collected. The analysis of CNS progression free survival and overall survival was performed and the effect of Osimertinib was defined. Results: There were 254 patients with advanced EGFR mutated NSCLCs. The prevalence of CNS metastasis was 32.28% (82 patients). There were 25.6% (21) of patients with definite evidence of CNS progression by imaging or clinical. In this group, Brain metastasis at first diagnosis was 61.9% (13 patients). EGFR TKIs was given as first line 42.9% (9 patients), second line 33.3% (7 patients), third line 19% (4 patients). Whereas one patient did not received EGFR TKIs. Most of EGFR TKIs treatment was first generation for 95% (19 patients). Osimertinib was given in 23.8% (5) of patients as second line, third line and fourth line for 2, 1 and 2 patients, respectively. The onset of CNS metastasis before EGFR TKIs was 76.2% when compared to 4.8%, 19% during EGFR TKIs and after EGFR TKIs, respectively. Treatment of brain metastasis was whole brain radiation for 85.7% (18 patients), followed by surgery with whole brain radiation for 14.3% (3 patients). The median CNS progression free survival was 14.00 (9.51,18.48) months. The median CNS progression free survival between no Osimertinib treatment and Osimertinib treatment was 13 (10.38,15.61) months and 21 (17.49,24.5) months, respectively. The median survival was 30.03 (19.6,40.45) months. The median survival between no Osimertinib treatment and Osimertinib treatment was 26.58 (18.96,34.20) months and NR (NR, NR), respectively. Conclusions: The prevalence of CNS progression was 25.6% in patients with EGFR mutated NSCLC in Thailand. Treatment with EGFR TKIs improved CNS progression free survival better than historical data.3rd generation EGFR TKIs Osimertinib in later line prolong clinical benefit of CNS Progression free survival and overall survival better than 1st generation EGFR TKIs alone.