(ChemotherapyAdvisor) – First-line bevacizumab non-gastrointestinal adverse event (AE) rates appear to be similar to those associated with chemotherapy alone among patients diagnosed with metastatic colorectal cancer (mCRC) after age 64, partly because patients with cerebrovascular conditions are less frequently prescribed bevacizumab, according to a database study published in Clinical Colorectal Cancer.

“First-line bevacizumab was not associated with increased AE (adverse event) incidence or risk of first AE compared with chemotherapy alone,” reported lead author Veena Shankaran, MD, of the Division of Public Health Sciences at Fred Hutchinson Cancer Research Center in Seattle, WA, and colleagues.

However, among patients with a history of pre-existing gastrointestinal (GI) conditions, risk of GI hemorrhage and perforation were associated with bevacizumab use (odds ratio [OR] 3.42; P=0.004 and OR 6.58; P<0.001, respectively), the authors noted. 

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The study did not confirm a previously-reported association between bevacizumab and stroke risk, but the authors noted that patients with a history of cerebrovascular conditions like stroke were less likely to have been prescribed bevacizumab in this study population.

The researchers identified 6,821 patients in the National Cancer Institute and Surveillance, Epidemiology and End Results and Medicare databases who had been diagnosed with mCRC in the pre-bevacizumab approval era (2001-2003) and post-approval era (2005-2007), and collected data on patients’ pre-existing cardiovascular, cerebrovascular, GI, and pulmonary conditions associated with elevated bevacizumab AE risk in the year before mCRC diagnosis, they reported.

Among patients diagnosed during 2005-2007, there was no difference in time to AE between patients treated with chemotherapy alone and those who also received bevacizumab (P=0.73), the authors reported.

“Most patients (57%) experienced some type of adverse event after the index date (55% in 2001-2003 and 60% in 2005-2007),” the researchers reported. But when chemotherapy-alone AE rates for 2001-2007 were compared with chemotherapy plus bevacizumab in 2005-2007, no difference was found (P=0.55).

Non-white patients with mCRC and patients older than age 74 were less likely to receive bevacizumab, the study authors found. Among patients diagnosed during 2005-2007, 19% received first-line bevacizumab overall, but rates of bevacizumab administration were lower among patients age 75 years or older (OR 0.41; 95% CI, 0.36-0.47) and nonwhite patients (OR 0.67; 95% CI, 0.55-0.81).

Patients with higher comorbidity indices and pre-existing cerebrovascular disease also were less likely to have received bevacizumab, the coauthors reported.

The study was funded by Genentech.