1704P - Prospective feasible study to evaluate neoadjuvant-synchronus S-1 + RT for locally advanced rectal cancer: a multicenter phase-II trial (UMIN ID03396)

Date 01 October 2012
Event ESMO Congress 2012
Session Poster presentation III
Topics Anti-Cancer Agents & Biologic Therapy
Rectal Cancer
Surgery and/or Radiotherapy of Cancer
Presenter Masafumi Inomata
Authors M. Inomata
  • Department Of Gastroenterological Surgery, Oita University Faculty of Medicine, 8795593 - Yufu/JP



Fluorouracil-based chemoradiotherapy (CRT) is regarded as a standard perioperative treatment in locally advanced rectal cancer. We investigated the efficacy and safety of substituting fluorouracil with the oral prodrug TS-1.


A multi-institutional (17 specialized centers), interventional phase II trial, was conducted from April 2009 to August 2011.This study is registered with UMIN-CTR, number C003396. For inclusion, patients must fulfill the following requirements before neoadjuvant CRT: (i) histologically proven rectal carcinoma; (ii) tumor located in the rectum (upper,lower); (iii) cancer classified as T3-4, N0–3 and M0; Two cycles of neoadjuvant CRT with TS-1 (100 mg/m2 on days 1-5, 8-12, 22-26, and 29-33) is administered, and irradiation (total 45Gy/25fr, 1.8Gy/day, on days 1-5, 8-12, 15-19, 22-26, and 29-33) is performed. Total mesorectal excision with D3 lymphadenectomy is performed during the 4th and 8th week after the end of the neoadjuvant CRT. The primary end-point is rate of complete treatment of neoadjuvant CRT. Secondary endpoints are response rate of neoadjuvant CRT, short-term clinical outcomes, rate of curative resection, and pathological response (grade2/3).


This trial included 37 patients. A complete treatment of neoadjuvant CRT was found in 83.3% of patients (95%CI;71.2 ∼ 95.5%), and an adverse event (grade 3/4) occurred in 4 patients(11.1%). A rate of an overall downstaging (PR/CR;RECIST 1.0) was 83.3% (95%CI; 71.2 ∼ 95.5%), and a pathologic response rate was 50.0% (95%CI; 33.7 ∼ 66.3%).


Our prospective phase-II study demonstrated that a neoadjuvant-synchronus TS-1 + RT for locally advanced rectal cancer was feasible in terms of pathological response and adverse events.


All authors have declared no conflicts of interest.