Complications associated with erythropoietin stimulating agents (ESAs) in patients with metastatic breast cancer: A surveillance, epidemiology, and end results (SEER)–Medicare study

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1034 Background: Results of recent clinical trials suggest that the use of ESAs is associated with adverse outcomes. ESAs increase the risk for thrombotic events and have the potential of decreasing survival. Guidelines recommend the use of ESAs in patients with chemotherapy-induced anemia being treated with non curative intent. In this population-based study, we sought to evaluate the thromboembolic effects associated with the use of ESAs in patients receiving chemotherapy for metastatic breast cancer. Methods: Retrospective cohort study using the SEER-Medicare linked database. Patients with stage IV breast cancer diagnosed from 1995–2002, who were 66 and older, were treated with chemotherapy, and had full coverage of Medicare A and B were identified. Patients with end stage renal disease were excluded. ICD-9 and HCPCS codes were used to identify the use of ESAs, chemotherapy, comorbidities, and complications of therapy. Analyses were conduced using descriptive statistics, logistic regression, and Cox proportional hazard models. Results: 1411 women were included, 519 (36.8%) received ESAs and 892 (63.2%) did not; median age was 73 and 74 years old respectively. Median time from diagnosis to first ESA dose was 6 months, median number of ESAs doses was 8.5. In univariate analysis, patients receiving ESAs had higher rates of MI/CAD (38% vs 32.9% p = 0.051), thrombosis (32.4% vs 23.2% p = 0.0002), phlebitis (21.4% vs 12.6% p < 0.0001), and transfusion (37.76% vs 19.4% p < 0.0001), with no difference in the rate of stroke or pulmonary embolism. Multivariate analysis showed HR for MI/CAD 1.29 (1.01–1.66); thrombosis 1.5 (1.116–1.93), phlebitis 1.79 (1.32–2.43), and transfusion 2.65 (2.05–3.43). Significant dose effect was evident for the thrombosis and phlebitis outcomes for patients receiving more than 5 ESAs doses. Conclusions: The use of ESAs in patients with metastatic breast cancer increases the risk of thrombosis and phlebitis, with evidence of a dose-dependent effect. Patients receiving ESAs were more likely to have blood transfusions. These data support current practice of using ESAs for minimum necessary time to reduce risk of complications. No significant financial relationships to disclose.