Modified FOLFOX6 With or Without Radiation Versus Fluorouracil and Leucovorin With Radiation in Neoadjuvant Treatment of Locally Advanced Rectal Cancer: Initial Results of the Chinese FOWARC Multicenter, Open-Label, Randomized Three-Arm Phase III Trial

Purpose Total mesorectal excision with fluorouracil-based preoperative chemoradiotherapy and postoperative chemotherapy is a standard treatment of locally advanced rectal cancer. This study investigated the addition of oxaliplatin with and without preoperative radiotherapy. Methods In this multicenter, open-label, phase III trial, we randomly assigned (1:1:1) Chinese adults (age 18 to 75 years) with locally advanced stage II/III rectal cancer to three treatments: five 2-week cycles of infusional fluorouracil (leucovorin 400 mg/m2, fluorouracil 400 mg/m2, and fluorouracil 2.4 g/m2 over 48 h) plus radiotherapy (46.0 to 50.4 Gy delivered in 23 to 25 fractions during cycles 2 through 4) followed by surgery and seven cycles of infusional fluorouracil, the same treatment plus intravenous oxaliplatin 85 mg/m2 on day 1 of each cycle (modified FOLFOX6 [mFOLFOX6]), or four to six cycles of mFOLFOX6 followed by surgery and six to eight cycles of mFOLFOX6. Random assignment was performed by using computer-generated block randomization codes. The primary end point was 3-year disease-free survival. Secondary end points of histopathologic response and toxicity are reported. Results A total of 495 patients were enrolled from June 2010 to February 2015; 475 were evaluable (fluorouracil-radiotherapy, n = 155; mFOLFOX6-radiotherapy, n = 157; mFOLFOX6, n = 163). In the fluorouracil-radiotherapy, mFOLFOX6-radiotherapy, and mFOLFOX6 groups, the rate of pathologic complete response (pCR) was 14.0%, 27.5%, and 6.6%, and downstaging (ypStage 0 to 1) was achieved by 37.1%, 56.4%, and 35.5% of patients, respectively. Higher toxicity and more postoperative complications were observed in patients who received radiotherapy. Conclusion mFOLFOX6-based preoperative chemoradiotherapy results in a higher pCR rate than fluorouracil-based treatment. Perioperative mFOLFOX6 alone had inferior results and a lower pCR rate than chemoradiotherapy but led to a similar downstaging rate as fluorouracil-radiotherapy, with less toxicity and fewer postoperative complications.