Study type: Epidemiological study (observational study)

Extremely low-frequency magnetic fields and survival from childhood acute lymphoblastic leukemia: an international follow-up study. epidem.

Published in: Blood Cancer J 2012; 2: e98

Aim of study (acc. to author)

An international follow-up study was initiated to investigate the association between exposure to extremely low-frequency magnetic fields and survival from childhood acute lymphoblastic leukemia. The pooled analysis was based on data from following studies carried out in Canada (McBride et al., 1999), Denmark (Olsen et al., 1993), Germany (Michaelis et al., 1998 ), New Zealand (Dockerty et al., 1999), Sweden (Feychting et al., 1993), UK (UK Childhood Cancer Study Investigators, 1999), USA (Linet et al., 1997), Germany (Schüz et al., 2001), Japan (Kabuto et al., 2006), and USA (Foliart et al., 2006),

Further details

Previous studies (Foliart et al., 2006 and Svendsen et al., 2007) showed poorer survival from childhood acute lymphoblastic leukemia related to exposure to extremely low-frequency magnetic fields developing the hypothesis that extremely low-frequency magnetic fields may promote growth of leukemia cells. Demonstrating an effect of extremely low-frequency magnetic fields on disease progression would therefore directly support the biological plausibility.
In the present study, children with acute lymphoblastic leukemia were followed up to 10 years from diagnosis to collect information on survival, relapse, a second malignant neoplasm, or death.
For a prognostic risk designation the children were divided into the low risk group (children with age below 10 years and diagnostic white blood cell count below 50 000/ml) and the high risk group (children aged 10 years or older or with a white blood cell count above or equal to 50 000/ml).

Endpoint/type of risk estimation

Exposure

Assessment

Exposure groups

Group Description
Reference group 1 magnetic field exposure: ≤ 0.1 µT
Group 2 magnetic field exposure: 0.1 - 0.2 µT
Group 3 magnetic field exposure: 0.2 - 0.3 µT
Group 4 magnetic field exposure: > 0.3 µT

Population

Study size

Type Value
Total 3,073
Statistical analysis method:

Conclusion (acc. to author)

Most of the children with acute lymphoblastic leukemia (88%) were exposed to extremely low frequency magnetic fields of ≤ 0.1 µT , with this proportion varying by country, ranging from 99% in Denmark to 69% in one of the US studies. 68 cases (2%) were in the high exposure group of > 0.3 µT, the majority (n=42) coming from the two US studies.
In this large pooled analysis of more than 3000 children diagnosed with acute lymphoblastic leukemia in eight countries, no statistically significant associations were observed between exposure to extremely low frequency magnetic fields and event-free survival or overall survival of acute lymphoblastic leukemia. The authors conclude that exposure to extremely low frequency magnetic fields has no impact on the survival probability or risk of relapse in children with acute lymphoblastic leukemia.

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