Second-line chemotherapy use in metastatic colon cancer varies by disease responsiveness

Background: Improved survival of patients with metastatic colorectal cancer (CRC) has been shown to correlate with increased utilization of the 3 active cytotoxic chemotherapeutic agents: 5-fluorouracil (5-FU), irinotecan, and oxaliplatin, usually administered in 2 lines of therapy. However, it is unclear which patient, disease, and treatment characteristics are associated with the utilization of a second-line regimen. Patients and Methods: We performed a retrospective chart review. Patients with metastatic CRC treated with bevacizumab outside of a clinical trial and any infusional 5-FU/leucovorin (LV) regimen off-protocol (ie, 5-FU/LV/irinotecan [FOLFIRI]/bevacizumab or 5-FU/LV/oxaliplatin [FOLFOX]/bevacizumab) at the University of Texas M. D.Anderson Cancer Center between February 2004 and September 2005 were included. Prespecified characteristics of age, tumor burden, severe toxicity, and front-line regimen efficacy were compared with exploratory analyses of additional patient, disease, and treatment characteristics. Results: Eighty-seven sequential patients treated with the specified front-line regimens were identified. Seventy-six percent of the eligible patients were treated with a second-line regimen. Despite equal treatment durations, patients with a better response of stable disease were significantly less likely to receive a third cytotoxic agent than patients with a partial response (68% vs. 95%; odds ratio, 8.2; P = .02) due to declining performance status (86%) or patient preference (14%). This was associated with a decreased 2-year overall survival (86% vs. 55%). Neither age, tumor burden, nor development of toxicities were associated with a different utilization of a second-line regimen. Conclusion: Failure to obtain a response to initial chemotherapy for metastatic disease appears to be associated with decreased utilization of a second-line regimen.