Exposure to Magnetic Fields and Survival after Diagnosis of Childhood Leukemia: A German Cohort Study
- 1Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, Copenhagen, Denmark and 2German Childhood Cancer Registry, Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), University of Mainz, Mainz, Germany
- Requests for reprints:
Joachim Schüz, Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, DK-2100 Copenhagen, Denmark. Phone: 45-3525-7655; Fax: 45-3532-7731. E-mail: joachim{at}cancer.dk
Abstract
Inspired by a recent U.S. study showing poorer survival among children with acute lymphoblastic leukemia (ALL) exposed to magnetic fields above 0.3 μT, we examine this relationship in a German cohort of childhood leukemia cases derived from previous population-based case-control studies conducted between 1992 and 2001. A total of 595 ALL cases with 24-h magnetic field measurements are included in the analysis with a median follow-up of 9.5 years. We calculate the hazard ratios (HR) using the Cox proportional hazards model for overall survival, adjusted for age at diagnosis, calendar year of diagnosis, and gender. Elevated hazards are found for exposures between 0.1 and 0.2 μT [HR, 2.6; 95% confidence interval (95% CI), 1.3-5.2], based on 34 cases with 9 deaths as well as for exposures above 0.2 μT (HR, 1.6; 95% CI, 0.6-4.4), based on 18 cases with 4 deaths. After adjustment for prognostic risk group, the hazard for exposures above 0.2 μT increases to HR, 3.0 (95% CI, 0.9-9.8). In conclusion, this study is generally consistent with the previous finding; however, we report the excess risk at field levels lower than those in the U.S. study. In all, the evidence is still based on small numbers, and a biological mechanism to explain the findings is not known. (Cancer Epidemiol Biomarkers Prev 2007;16(6):1167–71)
Footnotes
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Grant support: The original EMF study was supported by a grant from the German Ministry for the Environment, Reactor Safety, and Nature Protection. This analysis was done on core budgets from the University of Mainz and the Danish Cancer Society.
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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- Accepted March 13, 2007.
- Received October 18, 2006.
- Revision received March 7, 2007.
