Chemotherapy treatments for metastatic colorectal cancer: Is evidence-based medicine in practice?

Purpose: The optimal regimen for the treatment of metastatic colorectal cancer (CRC) remains uncertain. We sought to document clinicians' treatment recommendations and determine the motivation behind them. Materials and Methods: A postal questionnaire was sent to all members of the Medical Oncology Group of Australia concerning chemotherapy treatment options in the setting of metastatic CRC. Results: The response rate was 59.7% (n = 188). One hundred sixty-two physicians (86%) treated patients with CRC. Of the 162 physicians, 92.6% (n = 150) recommended oxaliplatin-based regimens as first-line treatment for CRC due to perceived superior efficacy (66.9%; n = 107) or toxicity profile (17%; n = 27). Fluorouracil (FU), leucovorin (LV), and oxaliplatin (FOLFOX6) was the most popular regimen (59.3%; n = 98). Calcium and magnesium to prevent oxaliplatin-related neurotoxicity was routinely used by 34.6% of physicians (n = 56) from cycle 1. Despite the lack of phase III data at the time, 8.6% of physicians (n = 14) selected capecitabine and oxaliplatin (XELOX) a preferred first-line regimen; 61.7% of physicians (n = 100) recommended FU, LV, and irinotecan (FOLFIRI) second-line treatment. Concerning LV dose, one third of physicians (33.3%; n = 54) selected 20 mg/m² and one third of physicians (32.7%, n = 53) selected 200 mg/m², with 25.3% of physicians (n = 41) using a fixed 50 mg bolus. Conclusion: This survey demonstrated considerable variation regarding recommended chemotherapy for patients with metastatic CRC. Of considerable concern is the use of calcium and magnesium based on retrospective data alone. Given that this variation in practice may significantly impact patient outcomes, additional studies are required to improve understanding of physician attitudes and the motivations behind treatment decision making.