The Greta study: generating real-world evidence about bevacizumab treatment of metastatic Colorectal Cancer by linking Cancer registries and healthcare databases in Italy

OBJECTIVES: Based on the results of randomized clinical trials, bevacizumab plus chemotherapy is currently recommended as first­line treatment for metastatic colorectal cancer (mCRC). However, scant real­world data are available about effectiveness of bevacizumab­containing therapy used in patients with mCRC in Italy. The GRETA observational cohort study was designed for comparing overall survival (OS) of mCRC patients treated with first­line bevacizumab plus chemotherapy (B+CT), as compared to CT alone, in the real­world setting of Italian clinical practice, by linking cancer registries and healthcare utilization (HCU) databases. METHODS: Incident mCRC patients were identified during the period 2010­2012 from five population­based cancer registries, representing the 5.4% of the entire Italian population. Cases were linked to Regional HCU databases, in order to obtain the entire pathway of health services provided to each patient. Patients who started a first­line treatment with either B+CT or CT alone were included in the study cohort. A propensity score (PS) method was applied in order to take into account residual confounding. RESULTS: A study cohort of 480 subjects was selected, of which 101 received first­line B+CT and 379 CT alone. The median OS was 22.5 and 14.6 months in patients treated with or without bevacizumab, respectively (p=0.011). The corresponding adjusted hazard ratio (HR) was 0.82 (95% CI 0.62­1.08). The HR resulting from the PS matched analysis was 0.86 (95% CI 0.56­1.33). The gain in median OS was 8.3 months among patients aged less than 70 years (p=0.087) and 4.3 months among those aged 70 years or older (p=0.221). CONCLUSIONS: Despite not statistically significant, the addition of bevacizumab to CT showed a beneficial effect on OS, in the real­world clinical practice of mCRC patients in Italy. The gain in OS is comparable to that from the pivotal trial.