Registries and Randomized Trials in Assessing the Effects of Bevacizumab in Colorectal Cancer: Is There a Common Theme?

Results (SEER) – based analysis of bevacizumab in the treatment of metastatic colorectal cancer. Given the large number of patients with metastatic colorectal cancer who have been treated with bevacizumab— on and off clinical trials—there is now the potential to compare outcomes among multiple data sets. To the authors’ credit, SEER data sets can now be added to that list. These findings are particularly important if they truly reflect patients who are treated in everyday practice. The authors evaluated a large SEER-Medicare database that links patient diagnostic codes with billing records and clinical information, including survival. The key finding of this study was that, in the overall population, there was a statistically significant benefit from the addition of bevacizumab to fluorouracil-based chemotherapy. However, this benefit was felt to be “modest” and “no more than marginally effective.” Moreover, subset analyses found little to no benefit in patients treated with oxaliplatin. These findings, or at least the conclusions, seem to depart from the majority of previously published data from randomized controlled clinical trials (RCTs), registries, and meta-analyses, including those that have focused on elderly patients. 2-13 How can this discordance be reconciled? First, the primary end point of the current SEER-Medicare anal