Multicenter randomized phase II clinical trial of preoperative chemoradiotherapy by S-1 versus UFT to rectal cancer for personalized therapy (UMIN ID: 000001704).

Abstract

499 Background: Preoperative chemoradiotherapy (CRT) in rectal cancer reduces the local recurrence rate after operation and preserves the anus, but it is difficult to predict the effects of CRT. Multicenter randomized phase II clinical trial of preoperative chemoradiotherapy by S-1 vs UFT for rectal cancer was conducted to compare the toxicity and efficacy of CRT using oral DPD-inhibitory fluoropyrimidines (UFT versus S-1, (UMIN ID: 000001704)) in patients with locally advanced rectal cancer. Methods: In this randomized phase II study, during April 2008 to October 2010, rectal cancer patients (n=59) who underwent preoperative CRT were randomly divided into two groups; S-1 group (n=30, 80 mg/m2/day, 5 days/w x 4 w), and UFT (n=29, 300 mg/m2/day, 5 days/w x 4 w). Both groups were combined with 40Gy radiotherapy (2 Gy ×5 days/w × 4 weeks,total 40 Gy). The pathological response rate, clinical response rate by RECIST, and frequency of adverse events of CRT were compared between S-1 group and UFT group. Results: Response to CRT determined by histopathologic examination of surgically resected specimens and RECIST were as follows: responders (grade 2 or 3) were 60% (S-1) and 52% (UFT) (p=0.52). S-1 group showed 54% of response rate in pathological response, whereas UFT group showed 45% (p=0.43). In adverse events, frequence of Grade 2 and 3 diarrhea was significantly higher in S-1 group compared with UFT group. There was no difference between the two groups in compliance (S-1group: 83%, UFT group: 97%). Conclusions: Both S-1 and UFT were safely used for preoperative CRT. S-1 tended to show higher response rate than UFT, although diarrhea in S-1 was higher than in UFT. Clinical trial information: 000001704.