Risk of bevacizumab-associated gastrointestinal perforation in patients with colorectal cancer and noncolorectal cancer

Abstract

9622 Background: Bevacizumab is a recombinant humanized monoclonal antibody that inhibits vascular endothelial growth factor. It is a widely used angiogenesis inhibitor in the treatment of colorectal cancer (CRC) and other solid tumors. Gastrointestinal (GI) perforation is a potentially fatal adverse event associated with bevacizumab, but the risk unclear. This study was conducted to determine the risk of developing GI perforation among CRC and non-CRC patients receiving bevacizumab. Methods: Databases from PUBMED and the Web Science from January 1966 until July 2008 and abstracts presented at the American Society of Clinical Oncology conferences from January 2000 to through July 2008 were searched to identify relevant studies. Eligible studies included prospective phase III clinical trials in which standard anti-neoplastic therapy was administered with and without the use of bevacizumab with available data for GI perforation. Summary incidence rate, relative risk (RR), and 95% confidence interval (CI) were calculated using fixed or random effect models based upon the heterogeneity of the included studies. Results: A total of 12084 patients with various solid tumors from 14 phase III trials were included for analysis. Among patients receiving bevacizumab, the incidence of GI perforation was 0.8% (95% CI: 0.6–1.1%), and RR was 2.0 (95% CI: 1.1–3.8, p = 0.028) in compared with controls. The risk of GI perforation was significantly increased in patients receiving bevacizumab at 5 mg/kg/week (RR 2.6, 95% CI: 1.0–6.6, p=0.04), but not at 2.5 mg/kg/week (RR=1.5, 95%CI: 0.7–3.3, p=0.3). Among 2151 patients with CRC, the incidence of GI perforation was 0.8% (95% CI: 0.5–1.6%); while for 2.999 patients with non-CRC malignancies, the incidence of GI perforation was 0.7% (95% CI: 0.5–1.1%); The relative risk of GI perforation varied with tumor type, with significantly increased risk observed in patients with CRC (RR = 3.1, 95% CI: 1.2–8.2, p<0.023), but not non-CRC (RR=1.5, 95% CI: 0.67–3.4, p=0.3). Conclusions: There is a significant difference in the risk of developing GI perforation in CRC and non-CRC patients receiving bevacizumab with a higher relative risk in patients with CRC. Further investigation into the etiology of this difference is recommended. No significant financial relationships to disclose.