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Originally published as JCO Early Release 10.1200/JCO.2005.04.0014 on May 15 2006 © 2006 American Society of Clinical Oncology. Stroke Rates and Risk Factors in Patients Treated With Radiation Therapy for Early-Stage Breast Cancer
From the Radiation Oncology Department; University of Michigan Cancer Center Biostatistics Core; and the University of Michigan School of Medicine, Internal Medicine Department, Ann Arbor, MI Address reprint requests to Lori J. Pierce, MD, Department of Radiation Oncology, University of Michigan School of Medicine, 4308 Cancer and Geriatrics Center, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0010; e-mail: ljpierce{at}umich.edu PURPOSE: To examine whether stroke risk is elevated in American breast cancer patients treated with modern techniques, as well as whether supraclavicular radiation therapy (RT) is associated with increased risk. METHODS: Observed rates of stroke in 820 eligible early-stage breast cancer patients treated at the University of Michigan Hospital (Ann Arbor, MI) were compared with expected rates. Relationships between potential risk factors and actuarial rate of first stroke were analyzed. RESULTS: Median follow-up was 6.8 years. Twenty patients had at least one cerebrovascular accident (CVA) in follow-up; 35 patients had at least one CVA or transient ischemic attack (CVA/TIA). The standardized incidence ratios were 1.74 (0.94 to 2.37) for CVA and 1.68 (1.003 to 2.06) for CVA/TIA. The absolute excess risk per 1,000 patients per year was 1.67 for CVA and 2.76 for CVA/TIA. On bivariate analysis, factors significantly associated with actuarial rate of first CVA included hypertension (P = .002), age (P < .0001), coronary artery disease (P = .001), atrial fibrillation (P = .009), and supraclavicular RT (P = .021). Factors associated with CVA/TIA were hypertension (P < .001), coronary artery disease (P = .002), and age (P < .0001). Tamoxifen use alone was not significant (P = .19), but tamoxifen combined with baseline hypertension led to increased risk of CVA/TIA (log-rank P < .0001). On multivariate analysis, only age (P < .001) and hypertension (P = .003) remained significant predictors of CVA/TIA. Age was the only significant predictor of CVA alone (P < .001). CONCLUSION: American breast cancer survivors may have an elevated risk of stroke compared with the general population, but the absolute excess risk is low. This study found no significant association between supraclavicular RT and stroke after controlling for other factors. Presented in abstract form at the San Antonio Breast Cancer Symposium, San Antonio, TX, December 8-12, 2005. The authors certify that this is an original unpublished work. Authors disclosures of potential conflicts of interest and author contributions are found at the end of this article. This article has been cited by other articles:
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Copyright © 2006 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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