Survival and lifetime costs associated with first-line bevacizumab use in older patients with metastatic colorectal cancer

Introduction: The objective of this study was to investigate clinical effectiveness and incremental lifetime costs associated with first-line bevacizumab in older patients with metastatic colorectal cancer (mCRC).

Methods: Patients diagnosed with mCRC in 2004-2007 were identified from the Surveillance, Epidemiology, and End Results-Medicare database and stratified by first-line treatment (no chemotherapy [CTx], CTx alone, CTx plus bevacizumab). The impact of first-line bevacizumab on survival was investigated using a propensity score adjusted multivariate Cox proportional hazards model. Mean lifetime costs for each cohort were calculated using Medicare claims for all services rendered between diagnosis and end of follow-up, adjusting for death and censoring.

Results: A total of 4,414 patients (mean age: 77.3 years) were identified, of whom 15% received first-line bevacizumab. Among first-line-treated patients, bevacizumab receipt was associated with improved overall survival (hazard ratio: 0.85 [95% confidence interval: 0.75-0.97]; p = .013), and this benefit was limited to patients who received >1 month of bevacizumab therapy. Median and mean survival were greatest in patients treated with CTx plus bevacizumab relative to CTx alone (CTx plus bevacizumab median 19.4 months [mean 28.0 months] vs. CTx alone median 15.1 months [mean 22.9 months]; p < .001), as were mean lifetime costs (mean per patient cost $143,284 vs. $111,280). Compared with CTx alone, CTx plus bevacizumab was associated with a 5.1-month increase in mean survival and a $32,004 increase in mean lifetime treatment costs, with an incremental cost of $75,303 per life-year gained.

Conclusion: Bevacizumab use is associated with longer survival than CTx alone in older patients treated in real-world clinical settings, at an incremental cost of $75,303 per life-year gained.