Treatment patterns and clinical outcomes of metastatic gastric cancer in South Korea: real-world evidence from retrospective electronic medical records data

Abstract

Background Five-year survival of patients with metastatic gastric cancer (mGC) is poor. Tumor characteristics, timing of diagnosis, and treatment patterns differ between patients from Eastern and Western regions. Therefore, we aimed to evaluate treatment patterns and outcomes of patients with mGC in South Korea. Methods This retrospective study aimed to analyze electronic medical records.Treatment patterns were evaluated in 2,229 patients, and clinical outcomes were assessed in 2,083 patients. Results The median age of the included patients was 60 (range, 18-92) years (62.8%, male; 95.5% had Eastern Cooperative Oncology Group performance status score of 0-1). Among tested patients, HER2-positivity, microsatellite instability high/deficient mismatch repair (MSI-H/dMMR), and PD-L1 22C3 Combine Positive Score >= 1 rates were 16.0%, 4.7%, and 49.1%, respectively. Of the 2,353 patients, 94.7%, 68.0%, and 52.9% received first-line (1 L), second-line (2 L), third-line (3 L) therapy, respectively. Platinum doublets were used for 1 L (61.3%); paclitaxel plus ramucirumab, 2 L (50.6%); and, irinotecan-based therapy, 3 L (51.1%).The median overall survival (OS) was 3.8 and 16.3 months in the untreated and treated patients, respectively. Overall, HER2-positive patients treated with HER-2 targeted agent had a longer OS (19.1 months), and those treated with combined HER2-targeted plus immune checkpoint inhibitor (ICI) therapy (23.1 months) had the longest OS. In HER2-negative patients, OS was 15.7 months with chemotherapy, and 17.6 months with combined chemotherapy plus ICI. No survival differences were found between patients treated with oxaliplatin and cisplatin in 1 L, irinotecan and taxane in 2 L/3L, and across 2 L to 3 L sequences. Conclusions A survival benefit was observed with multiple lines of therapy, particularly with immune checkpoint inhibitor (ICI) therapy, in both HER2-positive and HER2-negative patients. Our findings support the benefits of multiline personalized treatments in mGC.