Adverse events associated with bevacizumab and chemotherapy in older patients with metastatic colorectal cancer.

Background: The safety of bevacizumab in older mCRC patients is poorly understood. The purpose of this analysis was to determine the prevalence, incidence, and risk factors for treatment-related AEs in older bevacizumab recipients.

Patients And Methods: Patients age ≥65 were identified from SEER-Medicare and categorized by mCRC diagnosis pre and post bevacizumab approval (2001-2003 vs. 2005-2007). Preexisting conditions known to increase bevacizumab-related AE risk were identified in the year before diagnosis. Factors associated with bevacizumab receipt were identified using logistic regression. Incidence rates for all AEs and specific serious AEs were determined. Risk factors for first AE were determined by competing risks regression.

Results: Of 6821 patients, 3282 (48%) were diagnosed in 2005-2007 of whom 19% received first-line bevacizumab. Likelihood of bevacizumab receipt was lower in patients age ≥ 75 (odds ratio [OR], 0.41; 95% confidence interval [CI], 0.36-0.47), nonwhite patients (OR, 0.67; 95% CI, 0.55-0.81), patients with higher comorbidity index (OR, 0.52; 95% CI, 0.43-0.62), and patients with preexisting cerebrovascular disease (OR, 0.49; 95% CI, 0.33-0.73). AE incidence rate was not increased among first-line bevacizumab recipients relative to first-line chemotherapy recipients. In a competing risk regression adjusting for potential confounders, bevacizumab receipt (2005-2007) was not associated with an increased risk of first AE compared with chemotherapy alone (2001-2007) (hazard ratio, 0.97; 95% CI, 0.87-1.08).

Conclusion: In an older mCRC population, bevacizumab receipt was less likely in older (age ≥ 75) nonwhite patients with preexisting cerebrovascular comorbidities. First-line bevacizumab was not associated with increased AE incidence or risk of first AE compared with chemotherapy alone.