406. EXPLORING THE OPTIMAL TIMING OF MINIMALLY INVASIVE SURGERY FOR ESOPHAGEAL SQUAMOUS CELL CARCINOMA AFTER NEOADJUVANT CHEMORADIOTHERAPY

Abstract Background Neoadjuvant chemoradiotherapy has gradually become a first-line treatment for esophageal squamous cell carcinoma patients. After the completion of neoadjuvant chemoradiotherapy, patients usually undergo minimally invasive surgery to ensure complete removal of the tumor and lymphatic tissue. However, the optimal interval between neoadjuvant chemoradiotherapy and minimally invasive surgery is still an unknown factor, and whether it affects postoperative disease-free survival (DFS) and overall survival (OS) of patients remains unknown. Therefore, the main purpose of this study is to explore the specific impact of the interval between neoadjuvant chemoradiotherapy and minimally invasive surgery on patients, and to find the optimal interval time. Methods Patients who underwent neoadjuvant chemoradiotherapy and minimally invasive surgery from two institutions between October 2012 and September 2022 were included in this study. The time interval is defined as the days between the last time a patient receives neoadjuvant chemoradiotherapy and the execution of surgery. Determine the optimal interval truncation point using the surv_cutpoint function in the survminer package. The main research result is the OS and DFS of different interval groups. A multivariate Cox regression model was established to determine the main factors affecting Patient's OS. Construct a nomogram based on selected factors to meet clinical needs. Results 252 patients were included in the study. The average interval between patients undergoing neoadjuvant chemoradiotherapy and minimally invasive surgery is 59 days. The earliest interval for patients to undergo surgery is 28 days. Determine the optimal interval of 46 days based on the survminer package and divide the patients into two groups. The five-year OS rates for the short interval group and the long interval group were 82.6% and 61.0% (P = 0.023). The five-year DFS rates for the two groups were 67.6% and 48.2% (P=0.068). Multivariate Cox regression shows that the time interval, patient's sex, tumor differentiation, ypT, and ypN are the main factors affecting overall survival. Conclusions The interval between neoadjuvant chemoradiotherapy and minimally invasive surgery has a certain impact on patient survival, and it is recommended to undergo surgery between 28 and 46 days to improve patient prognosis and survival.