A Study of Avastin (Bevacizumab) Plus Crossover Fluoropyrimidine-Based Chemotherapy in Patients With Metastatic Colorectal Cancer.

This study will evaluate the efficacy and safety of adding bevacizumab to crossover fluoropyrimidine-based chemotherapy in patients with metastatic colorectal cancer who have experienced disease progression under first line treatment with standard chemotherapy plus bevacizumab. Participants will receive chemotherapy alone, or in combination with bevacizumab. The anticipated time on study treatment is until disease progression or unacceptable toxicity occurs. Participants are allowed to continue on bevacizumab, even after stopping chemotherapy.