Bevacizumab in Treating Patients Who Have Undergone First-Line Therapy for Metastatic Colorectal Cancer

RATIONALE: Monoclonal antibodies, such as bevacizumab, can block tumor growth in different ways. Some block the ability of tumor cells to grow and spread. Others find tumor cells and help kill them or carry tumor-killing substances to them. Bevacizumab may also stop the growth of tumor cells by blocking blood flow to the tumor. It is not yet known whether giving bevacizumab as maintenance therapy is more effective than observation in treating patients with colorectal cancer. PURPOSE: This randomized phase III trial is studying bevacizumab to see how well it works in treating patients who have undergone first-line therapy for metastatic colorectal cancer.

OBJECTIVES: Primary * To demonstrate that time to progression (TTP) without further treatment is not inferior to TTP with maintenance therapy comprising bevacizumab in patients with metastatic colorectal cancer and stable or responding disease after completion of standard first-line chemotherapy/bevacizumab treatment. Secondary * To evaluate the safety of bevacizumab maintenance therapy in these patients. * To assess the long-term cost implications of prolonged treatment with bevacizumab. OUTLINE: This is a multicenter study. Patients are stratified according to best response during first-line chemotherapy/bevacizumab treatment (complete response and partial response vs stable disease), duration of first-line treatment (16-20 weeks vs 21-24 weeks), type of chemotherapy used during first-line treatment (irinotecan and fluoropyrimidine vs oxaliplatin and fluoropyrimidine vs fluoropyrimidine monotherapy), disease burden (one organ with metastasis vs more than one organ with metastasis), and by participating center. * Arm I (bevacizumab maintenance therapy): Patients receive bevacizumab IV over 30 minutes on day 1. Treatment repeats every 21 days in the absence of disease progression or unacceptable toxicity. * Arm II (no maintenance therapy): Patients receive no further treatment; they are monitored for disease progression. After completion of study therapy or documentation of disease progression, patients are followed every 3 months for 1 year and then every 6 months for up to 5 years.