A real-world study on implementation of bevacizumab in a cohort of HER2-negative metastatic breast cancer patients:A study of the Southeast Netherlands Breast Cancer Consortium

Background The objective of this study was to analyze real-world use and effectiveness of bevacizumab in combination with taxanes as first-line treatment in HER2-negative metastatic breast cancer. Furthermore, we provided insight in first-line treatment choices, shortly before and after introduction of bevacizumab. Patients and methods Patients were diagnosed with HER2-negative metastatic breast cancer between 2007–2009. Data on patient and tumor characteristics, palliative treatment and outcome was collected. Progression-free (PFS) and overall survival (OS) curves were estimated with Kaplan-Meier method. Results From the included 650 HER2-negative metastatic breast cancer patients, 193 received first-line chemotherapy after introduction of bevacizumab of whom 33 (17%) received bevacizumab and taxane. Patients treated with bevacizumab-taxane were younger, had a trend towards less cardiovascular comorbidities, a longer metastasis-free survival and received more adjuvant chemo- and endocrine therapy as compared to patients treated with other first-line chemotherapy regimens. Twenty-four percent of patients receiving bevacizumab-taxane had no indication for bevacizumab or received this despite contraindication. Thirty-tree (17%) of 193 patients could have received bevacizumab, but were treated with other first-line therapies, of whom 21 received bevacizumab in second line or beyond. Median PFS of first-line bevacizumab-taxane was 6.0 months (95% CI 4.8–13.1). Median OS was 28.4 months (95% CI 14-undetermined). Conclusion Bevacizumab was prescribed less frequently than expected, offered to a selected population and frequently outside guideline recommendations. Early field research on the implementation, use and effectiveness of new drugs in daily practice is necessary to guarantee effective implementation of these drugs.