Laparoscopic Versus Open Surgery For Locally Advanced Rectal Cancer Following Neoadjuvant Chemoradiotherapy With S-1: Short- And Long-Term Outcomes Of Multicenter Prospective Phase Ii Trials

793Background: We have reported the effectiveness of neoadjuvant radiotherapy (RT) combined with S-1 in terms of compliance and pathologic response for locally advanced rectal cancer. In the present study, we aimed to evaluate the safety and efficacy of laparoscopic surgery for locally advanced rectal cancer following neoadjuvant RT combined with S-1 in comparison with open surgery. Methods: Two multicenter prospective phase II trials were conducted (UMIN003396, UMIN003398). A total of 63 patients with locally advanced rectal cancer classified as T3-4, N0-3, and M0 were enrolled, and neoadjuvant RT combined with S-1 and total mesorectal excision with D3 lymphadenectomy was performed. Of these, 57 patients were analyzed and divided into a laparoscopic group (LAP, n = 43) and open group (OP, n = 14). We evaluated the short- and long-term outcomes of laparoscopic surgery compared with open surgery by univariate and multivariate analyses. Results: In the patient background, there were no significant differenc...