ARM I: Patients receive oxaliplatin IV over 2 hours and leucovorin calcium IV over 2 hours on day 1 and fluorouracil IV continuously over 46-48 hours beginning on day 1. Patients are further randomized to receive bevacizumab or placebo* IV over 30-90 minutes on day 1. Courses repeat every 2 weeks in the absence of disease progression or unacceptable toxicity. NOTE: *As of 11/15/04, placebo is no longer part of treatment plan; all patients receive bevacizumab.