- Arm I: Patients receive modified FOLFOX-6 therapy comprising oxaliplatin IV over 2 hours and leucovorin calcium IV over 2 hours on day 1 and fluorouracil IV continuously on days 1-5. Treatment repeats every 14 days for 3 courses. Patients then undergo PET/CT scan. Patients with responsive disease (tumor metabolic activity decreased by ≥ 35%) receive 3 additional courses of FOLFOX-6 therapy and undergo concurrent radiotherapy (RT) (3D-conformal or intensity-modulated) once daily, 5 days a week, for approximately 6 weeks. Patients without responsive disease (tumor metabolic activity did not decrease by 35%) cross over to arm II during RT.