336. IMPACT OF TIME TO SURGERY AFTER CHEMORADIOTHERAPY ON TUMOR REGRESSION AND SURVIVAL IN THE MULTICENTER RANDOMIZED CONTROLLED NEORES II TRIAL

Abstract

Abstract Time to surgery after termination of neoadjuvant chemoradiotherapy for esophageal cancer has traditionally been 4–6 weeks. Observational studies have suggested that delay of surgery for up to three months may lead to improved tumor regression and better outcomes. NeoRes II is the first randomized trial to address this in esophageal cancer. No difference in surgical morbidity or mortality between early and delayed surgery was reported in a previous publication from the trial. A multicenter clinical trial with randomized 1:1 allocation of standard time to surgery of 4–6 weeks, or delay of surgery to 10–12 weeks, after termination of chemoradiotherapy. The primary endpoint was complete histological tumor regression in patients with adenocarcinoma. Secondary endpoints included tumor regression grade, tumor free resection margins and overall survival in all patients, and stratified by histological subtype. In total 249 patients were randomized, 204 with adenocarcinoma and 45 with squamous cell carcinoma. There was no significant difference in histological complete response between adenocarcinoma patients allocated to standard time to surgery (20.6%) compared to delayed (25.6%) surgery (P = 0.18). Tumor free resection margin was achieved in 97.4% after standard time to surgery and 97.1% after delayed surgery (P = 1.0). The median follow-up time for survival was 51 months. Delayed time to surgery was associated with a 35% higher overall mortality, hazard ratio 1.35 (95% CI:0.94–1.95), (P = 0.11). No significant difference in complete histological tumor regression or tumor free resection margins comparing standard and delayed time to surgery after chemoradiotherapy was observed. There was a non-significant trend towards inferior overall survival after delayed surgery, suggesting caution in delaying surgery for more than 6 weeks after neoadjuvant chemoradiotherapy.