Preoperative chemoradiotherapy and postoperative chemotherapy with 5-fluorouracil and oxaliplatin versus 5-fluorouracil alone in locally advanced rectal cancer: First results of the German CAO/ARO/AIO-04 randomized phase III trial.

Abstract

LBA3505 Background: The German CAO/ARO/AIO-94 trial established preoperative chemoradiotherapy (CRT), surgery, and postoperative chemotherapy with 5-FU as standard treatment for locally advanced rectal cancer. With this approach local relapse rates are below 10%. The development of distant metastasis is the predominant mode of failure. Integrating more effective systemic treatment into combined modality therapy was the goal of CAO/ARO/AIO-04. Methods: Between 7/2006-2/2010, patients with rectal cancer within 12 cm from the anal verge and clinical evidence of perirectal fat or lymph node involvement were randomly assigned to receive preoperative CRT, surgery, and adjuvant chemotherapy with 5-FU according to CAO/ARO/AIO-94 (arm 1), or preoperative CRT (50.4 Gy in 28 fractions) with 5-FU (250 mg/m2/days 1-14 and 22-35) and oxaliplatin (50 mg/m2/days 1, 8, 22, 29), surgery, and 8 cycles of adjuvant chemotherapy according to modified FOLFOX6 regimen (arm 2). Disease-free survival was the primary endpoint. We present early secondary endpoints, including acute toxicity, treatment compliance, and pCR-rates. Results: 637 patients were randomly assigned to arm 1 and 628 to arm 2. Full dose preoperative RT and full dose concurrent chemotherapy was delivered in 97% and 74% of patients in both arms, respectively. Preoperative grade 3/4 toxicity occurred in 21.6% in arm 1 and in 22.9% in arm 2. The R0-resection rate was 95.4% in both arms, and abdominoperineal resections were limited to 11.9% and 12.2% in arms 1 and 2, respectively. Overall postoperative complications were not different between both arms (21.0% and 21.9%). The pCR rate (ypT0N0) was 13.1% in arm 1 and 17.6% in arm 2 (p = 0.033, Cochran-Mantel-Haenszel Chi-Squared Test without continuity correction for conditional independence of pCR rate in the two treatment arms in each stratum). Conclusions: Inclusion of oxaliplatin to 5-FU based CRT was well tolerated and associated with increased pCR-rates compared with 5-FU-CRT alone. Longer follow-up is necessary to evaluate the primary endpoint, disease-free survival.