Complications associated with erythropoietin-stimulating agents in patients with metastatic breast cancer: a Surveillance, Epidemiology, and End Results-Medicare study.

backgroundThe authors evaluated the patterns of use and the risk of thromboembolic events (TEE) associated with erythropoietin-stimulating agents (ESAs) in older patients with metastatic breast cancer who were receiving chemotherapy.

methodsThe study was retrospective and used the SEER-Medicare linked database. Stage IV breast cancer patients diagnosed from 1995-2005, treated with chemotherapy, ≥66 years old, with full coverage of Medicare A and B were included. The World Health Organization's International Classification of Diseases (ICD-9) and the Healthcare Common Procedure Coding System (HCPCS) were used to identify the use of ESAs, chemotherapy, and complications of therapy. Analyses included descriptive statistics and logistic regression.

resultsOf 2266 women, 980 (43.3%) received ESAs, and 1286 (56.7%) did not. Patients diagnosed after 1999 or who received treatment with taxanes, anthracyclines, or vinorelbine were more likely to receive ESAs. Patients receiving ESAs had higher rates of stroke (18.5% vs 15.1%, P = .031); deep-vein thrombosis (DVT; 21.3% vs 14.4%, P<.001), other/unspecified thromboembolic event (TEE; 19.8% vs 14.7%, P = .001), and any clot (31.3% vs 23.4%, P<.0001). In multivariate analysis, patients receiving ESAs had increased risk for DVT (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.05-1.75), and any clot (OR, 1.26; 95% CI, 1.02-1.57). A dose-dependent effect was evident for stroke, DVT, other TEE, and any clot.

conclusionsIn this cohort of patients, the use of ESAs increased the risk of TEEs, with a dose-dependent effect for stroke, DVT, other TEE, and any clot. The data show that among patients treated with chemotherapy and ESAs for metastatic breast cancer, TEEs are a common event. Therefore, caution is recommended when using these agents.