508 patients with untreated metastatic colorectal cancer were randomly assigned to receive either FOLFOXIRI (fluorouracil, leucovorin, oxaliplatin and irinotecan) plus bevacizumab or FOLFIRI (fluorouracil, leucovorin and irinotecan) and bevacizumab (control group). Patients who received FOLFOXIRI and bevacizumab had improved progression-free survival compared with control patients (12.1 versus 9.7 months, P = 0.003), but also had an increased incidence of certain adverse events.