Risk of arterial thromboembolic events in patients with advanced colorectal cancer receiving bevacizumab

Background: Bevacizumab is an antiangiogenic mAb with efficacy against several cancers, but it is associated with risk of arterial thromboembolism (ATE). Further data are needed to determine the safety of bevacizumab.

Patients and methods: We recorded grade 3, 4, or 5 ATE events and other data (including age, baseline cardiovascular risk factors, history of ATE, and aspirin use) from 471 patients with metastatic colorectal cancer in the MAX (Mitomycin, Avastin, Xeloda) trial of capecitabine monotherapy versus capecitabine with bevacizumab with or without mitomycin C.

Results: Bevacizumab-treated patients had 12 grade 3, 4, or 5 ATEs (3.8% incidence). ATEs occurred in 2.1% of patients > 65 years, 5% of those with a history of ATE, and 5% of those with cardiac risk factors. Age, history of ATE, or vascular risk factors did not increase risk. Aspirin users had a higher incidence than nonusers (8.9% versus 2.7%) but had higher rates of vascular risk factors.

Conclusions: Bevacizumab was associated with a modestly higher risk of ATE, but safety was not significantly worse in older patients or patients with a history of ATE or vascular risk factors. The effect of aspirin in preventing ATE in patients receiving bevacizumab could not be determined from this study.