A multicenter phase II study of preoperative chemoradiotherapy with S-1 plus oxaliplatin for locally advanced rectal cancer (SHOGUN trial)

Abstract

PurposeThis study was designed to evaluate the safety and efficacy of adding oxaliplatin to preoperative chemoradiotherapy (CRT) with S-1 in patients with locally advanced rectal carcinoma (LARC). Patients and methodsThis was a multicenter phase II study in patients with histologically proven clinical stage T3 or T4 (any N, M0) LARC. Patients preoperatively received oral S-1 (80mg/m2/day on days 1–5, 8–12, 22–27, and 29–33) and infusional oxaliplatin (60mg/m2 days on 1, 8, 22, and 29) plus radiotherapy (50.4Gy), with a chemotherapy gap in the third week of radiotherapy. Pathological complete response (pCR) was the primary endpoint. Secondary endpoints included toxicity, compliance, R0 resection rate, and downstaging rate. ResultsA total of 45 patients were enrolled at six centers in Japan. All 45 patients received CRT, and 44 underwent operation. A pCR was achieved in 12 (27.3%) of the 44 patients who underwent surgery. Near-total tumor regression was confirmed in 47.7%. There were no grade 4 adverse events, and 11.1% of the patients had grade 3 adverse events. R0 resection was achieved in 95.5% of the patients. ConclusionPreoperative CRT with S-1 plus oxaliplatin had a high pCR rate and a favorable toxicity profile.