Safety of mFOLFOX6/XELOX as adjuvant chemotherapy after curative resection of stage III colon cancer: phase II clinical study (The FACOS study)

Purpose: Adjuvant chemotherapy with oxaliplatin combined with a fluoropyrimidine derivative is widely accepted as standard therapy for patients with stage III colon cancer, since few clinical data are available for Japanese patients. The FACOS trial investigated the tolerability of modified FOLFOX6 (mFOLFOX6) and XELOX regimens in Japanese colon cancer patients. Methods: Twelve cycles of mFOLFOX6 or 8 cycles of XELOX were given to patients with eligibility: stage III curatively resected colon cancer, performance status of 0–1, age from 20 to 75 years, and adequate organ function. The primary endpoint was 3-year disease-free survival. Secondary endpoints were the incidence of adverse events (AEs) and the completion rate of study therapy. Results: From April 2010 to April 2014, a total of 132 patients were enrolled. Safety was analyzed in 130 patients, with finalized data from 73 patients receiving mFOLFOX6 and 57 patients receiving XELOX. A total of 130 patients (100%) experienced AEs (any grade), and 52 patients (40.0%) experienced AEs of grade ≥ 3. No significant difference in the frequency of grade ≥ 3 AEs was observed between mFOLFOX6 and XELOX groups. Continuation of the planned cycle rate of protocol treatment was 69.9% in the mFOLFOX6 group and 68.4% in the XELOX group. Treatment was discontinued because of AEs in 14 patients (19.2%) in the mFOLFOX6 group and 8 (14.0%) in the XELOX group. Mean relative dose intensity for oxaliplatin was 78.0% in the mFOLFOX6 group and 82.8% in the XELOX group. Conclusion: As adjuvant chemotherapy for stage III colon cancer, mFOLFOX6/XELOX regimens are acceptable.