Effectiveness of First-Line Bevacizumab in Metastatic Colorectal Cancer: The Observational Cohort Study GRETA.

Background Scant real-world data exist on the clinical outcomes associated with the use of bevacizumab-containing chemotherapy (B+CT) in patients with metastatic colorectal cancer (mCRC). The primary objective of the GRETA cohort study was to compare the overall survival (OS) of patients with mCRC treated with first-line B+CT versus chemotherapy (CT) alone, in an Italian clinical practice setting. Materials and Methods Incident patients with mCRC were identified during the period 2010-2012 from five population-based cancer registries in Italy. Cases were linked to regional health care utilization databases to obtain the entire spectrum of health services provided to each patient. Patients starting a first-line treatment with B+CT or CT alone within 90 days from the diagnosis were included in the study cohort. A propensity score (PS) method was applied to account for residual confounding. Results Of 480 patients with mCRC included in the study cohort, 21.0 received first-line B+CT, and 79.0% received CT. Patients receiving B+CT were younger (p < .001) and underwent surgery more frequently (p = .001). The median OS was 22.5 and 14.6 months for B+CT and CT, respectively (p = .011). The corresponding hazard ratios adjusted by multivariate modeling and PS matched analysis were 0.82 (95% confidence interval [CI], 0.62-1.08) and 0.86 (95% CI, 0.56-1.33), respectively. Similar results were observed after subgrouping by age and surgery. Conclusion In this Italian real-world setting of unselected mCRC, the OS of patients treated with B+CT was consistent with previous observational and patient-registry studies. However, definitive evidence of an improvement in OS cannot be drawn.