Patients receive FOLFOX7 chemotherapy comprising oxaliplatin IV over 2 hours and leucovorin calcium IV over 2 hours on day 1 and fluorouracil IV over 46 hours beginning on day 1. Patients also receive oral celecoxib twice daily beginning on day 1. Treatment repeats every 14 days for 6 courses in the absence of disease progression or unacceptable toxicity. Patients with stable or responding disease stop treatment. If disease progression occurs during the chemotherapy-free interval, patients receive an additional 6 courses.