LAUSR

708Background: We have performed preoperative CRT for advanced lower rectal cancer patients using S-1 or UFT. To improve response rate, we are performing phase 2 trial of preoperative CRT using S-1/ Oxaliplatin /Bevacizumab (SOX+Bev) regimen. In this study, we show the results of the trial and the promising predictive factor. Methods: Twenty-five patients (SOX+Bev) and 59 patients (S-1 or UFT) were included in this study. S-1(80mg/m2), UFT(300mg/m2) were administered orally every day on radiation therapy, and S-1(80mg/m2,Oxaliplatin(40-60mg/m2),Bevacizumab(5mg/kg) were administered in SOX+Bev group. Total dose of radiation was 40Gy with four field technique. As a predictive factor, we measured miR-223 with real-time PCR using pre CRT biopsy specimens. Results: Clinical response by RECIST were as follows: SOX+Bev group: CR/PR/SD/PD = 1/21/3/0, S-1/UFT group: CR/PR/SD/PD = 1/32/26/0. Clinical response rate were 88% in SOX+Bev group, higher than 56.0% in S-1/UFT group. Pathological response grade were as fol...