This open-label trial of the treatment of colorectal cancer with cetuximab, a chimeric monoclonal antibody against the epidermal growth factor receptor (EGFR), showed that among patients with colorectal cancer that expressed EGFR and that had failed to respond to other treatments, overall survival and progression-free survival were better in those receiving cetuximab than in those receiving best supportive care alone. Among patients with colorectal cancer that expressed EGFR and that had failed to respond to other treatments, overall survival and progression-free survival were better in those receiving cetuximab than in those receiving best supportive care alone. Colorectal cancer has a worldwide annual incidence of 917,000 and is the second leading cause of cancer-related death in Western nations. 1 The cytotoxic agents irinotecan, oxaliplatin, and the fluoropyrimidines, as well as bevacizumab, the antibody against vascular endothelial growth factor A, have increased the median survival of patients with advanced colorectal cancer, 2 – 9 but in most patients the disease is incurable. Recent advances have led to the development of agents that specifically inhibit tumor growth. Epidermal growth factor receptor (EGFR) is often up-regulated in colorectal cancer. Cetuximab, a chimeric IgG1 monoclonal antibody that binds to the extracellular domain of EGFR, . . .