Trends in Chemotherapy Patterns and Survival of Patients with Advanced Gastric Cancer Over a 16-year Period: Impact of Anti-HER2-Targeted Agent in the Real-World Setting

Purpose This study aimed to evaluate the survivals of patients with metastatic or recurrent gastric cancer (MRGC) over a period of 16 years and to investigate the recent changes in chemotherapy patterns. Materials and Methods A total of 5,384 patients who received chemotherapy for MRGC between 2000 and 2015 were analyzed. The analysis focused on a comparison of the first-line chemotherapy between four periods: 2000-2003 (period 1), 2004-2007 (period 2), 2008-2011 (period 3), and 2012-2015 (period 4). Results There were 880 patients (16%) in period 1, 1,573 (29%) in period 2, 1,435 (27%) in period 3, and 1,496 (28%) in period 4. Cytotoxic doublet-based therapy was the most commonly used (78%) first-line chemotherapy, and the combination of trastuzumab and doublet chemotherapy was provided to 288 patients. The OS rates at 12 and 24 months were steadily improved as follows: 39.2% and 14.6% in period 1, 43.5% and 17.6% in period 2, 50.3% and 20.6% in period 3, and 51.7% and 24.1% in period 4, respectively (p < 0.001). Among the patients who received the doublet-based chemotherapy, the median OS of those who received trastuzumab was 18.0 months (95% CI, 15.5-20.6), while that of those who received other doublet therapies was 11.2 months (95% CI, 10.8-11.6). Conclusion The OS was improved over time with advancements in chemotherapy, particularly the introduction of the anti-HER2-targeted agent, which contributed to the increase in the number of long-term survivors and established the superiority of OS for the treatment of MRGC.