Venous thromboembolism (VTE) and erythropoiesis-stimulating agents (ESAs) in breast cancer: a single tertiary care center experience from the University of Arkansas for Medical Sciences (UAMS).

Abstract #6137 Introduction: ESAs have been associated with increased rates of death, myocardial infarction, stroke and venous thromboembolism(VTE) in dialysis patients especially when targeted to higher hemoglobin levels. VTE and progression of cancer have also been reported in cancer patients receiving ESAs with chemo- and/ or radiotherapy, without a strict correlation with hemoglobin levels. ESAs are the subject of intense scrutiny by the FDA and the center for Medicare and Medicaid Services. We conducted a retrospective cohort study of a relatively homogeneous group of breast cancer patients. The objectives were to detect any increased risk of VTE with ESA exposure, and to correlate it with the hemoglobin/hematocrit levels. Methods: Data were extracted from Logician, an electronic medical record database used in the Medical Oncology Clinic at UAMS. The study cohort included breast cancer patients treated at UAMS with chemotherapy between July 1, 2004 and July 1, 2007. Patients with prior history of VTE were excluded. The patients were followed until September 9, 2007 for ESA(Erythropoietin/Darbepoietin) exposure and development of VTE. The association between ESA exposure and VTE development was assessed using Cox regression with ESA exposure as a time-dependent covariate, and the results were reported as the hazard ratio (HR) along with associated chi-square statistic and p value. Results: 483 patients (482 female, 1 male) met the study inclusion criteria. Median (range) age was 56 yrs (27-89). 107 (22%) were African American, 361 (75%) were Caucasian, and 15 (3%) in other categories. 9 out of the total 483 pts (1.86%) developed a VTE [7 Deep Vein Thromboses (DVTs) and 2 pulmonary embolism (PE)]. 63 subjects (13%) were exposed to ESAs during the study period, and 1 of them developed a DVT. The mean Hgb/Hct in the 62 patients exposed to ESAs who did not develop VTE was 11.34/35.26; the 1 patient exposed to ESA with DVT had a Hgb/Hct of 12.5/37.9. Among the 420 patients not exposed to ESAs, 6 developed a DVT; their mean Hgb/Hct was 12.95/39.4. The 414 pts without a DVT had mean Hgb/Hct of 12.66/38.55. Comparisons of the Hgb/Hct values in the various groups with or without VTE and, with or without ESA exposure showed no significant differences between any of the groups. Cox regression showed little evidence of increased risk with ESA use for either VTEs in general (HR=1.83; X21=0.57, P=0.45) or DVT in particular (HR=1.08; X21=0.005, P=0.94). Conclusions: The number of VTEs in the study patients was very small, and much lower than previous reports. There was no evidence of increased risk of VTE from ESA exposure. However, due to the small number of events, this study lacked the power to detect an ESA effect unless the effect was huge. On the other hand, the very small number of VTEs in the ESA- exposed patients to may reflect our conservative ESA usage in breast cancer patients, and is reassuring that when used appropriately, ESA use is safe. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6137.