P1.225. The Impact of Metformin Use During Neoadjuvant Chemoradiotherapy in Esophageal Cancer Patients: A Propensity Score-Matched Nationwide Study

Abstract

Abstract Topic Esophageal Cancer: Surgical Treatment of Esophageal Cancer – long term outcomes Background Our previous study suggested an association between metformin use and complete response rates in esophageal cancer patients undergoing neoadjuvant concurrent chemoradiotherapy (CCRT). This study aims to evaluate the impact of metformin use during neoadjuvant CCRT on overall survival (OS) and cancer-specific survival (CSS) in esophageal cancer patients undergoing surgery, using a nationwide database. Methods We utilized the National Health Insurance Research Database to analyze patients diagnosed with esophageal cancer between January 2010 and December 2022. The index date was defined as the initiation of neoadjuvant therapy, with follow-up extending until December 2022. After propensity score matching (PSM), Cox regression analyses were performed to identify risk factors for survival outcomes, including OS and CSS. Results A total of 2,345 patients who underwent neoadjuvant CCRT followed by surgery were included, with 568 patients remaining after PSM. Metformin use was associated with a higher risk of all-cause mortality (HR: 1.28, 95% CI: 1.05–1.57, p = 0.014). The 5-year OS rates were 23.4% in the metformin group and 31.1% in the non-metformin group (p = 0.018). However, metformin use was not significantly associated with CSS, with 5-year CSS rates of 34.7% and 41.0% in the metformin and non-metformin groups, respectively (p = 0.140). Conclusion This is the first nationwide database analysis evaluating the impact of metformin use during CCRT on OS and CSS in esophageal cancer patients. Metformin use was associated with lower OS but did not significantly affect CSS. Further study should be needed.