Combination Chemotherapy for 3 Months or 6 Months in Treating Patients With Stage III Colon Cancer

OBJECTIVES: Primary Objective * To assess whether a 3-month modified FOLFOX 6 or XELOX treatment is not inferior to a 6-month modified FOLFOX 6 or XELOX treatment in terms of disease free survival (DFS) in patients with radically resected stage III colon cancer. Secondary Objectives * To assess whether 3-month modified FOLFOX 6 (6 cycles) or XELOX (4 cycles) treatment is not inferior to 6-month modified FOLFOX 6 (12 cycles) or XELOX (8 cycles) treatment in terms of overall survival (OS) in patients with radically resected stage III colon cancer * To evaluate the safety profiles of the treatment groups Tertiary Objectives * For patients who signed a specific informed consent, blood and tumour tissue samples will be stored, registered, and centralized in a data bank for translational research projects that will be further determined according to the literature and scientific knowledge at the time of the end of inclusion. (exploratory) * An economic evaluation at the country level will be conducted alongside the clinical evaluation. (exploratory) OUTLINE: This is a multicenter study. Patients are stratified according to center, T stage (1 or 2 vs 3 vs 4), N stage (1 vs 2), performance status (0 vs 1 vs 2), and age (\< 70 years vs ≥ 70 years). Patients are randomized to 1 of 2 treatment arms. * Arm I: Patients receive modified FOLFOX 6 comprising oxaliplatin IV over 2 hours, leucovorin calcium IV over 2 hours, and fluorouracil IV over 46 hours on day 1. Treatment repeats every 14 days for 6 courses (3 months). * Arm II: Patients receive modified FOLFOX 6 as in arm I. Treatment repeats every 14 days for 12 courses (6 months). Blood and tumor samples may be collected at baseline for pharmacogenetic and other analyses. After completion of study treatment, patients are followed up every 6 months for 8 years.