Leukemia

Leukemia (leukaemia in Commonwealth English) is a group of blood diseases characterized by malignancies (cancer) of the blood-forming tissues. Leukemia is the most common childhood cancer in the industrialised world; in the UK, around one in 2000 children are affected.

Causes

All leukemias are due to mutations in the DNA. Chromosomal translocations (crossing over of parts of chromosomes to others) are common, disrupting specific genes that mediate cell division rate. Mutations may occur spontaneously or as a result of exposure to radiation or carcinogenic substances. Cytogenetics and immunophenotyping are two laboratory investigations used to determine the type and aggressiveness of the leukemia and the necessity of urgent and active treatment, as well as an indication of prognosis.

Related Topics:
Mutation - DNA - Chromosomal translocation - Chromosome - Gene - Radiation - Carcinogenic - Cytogenetics - Immunophenotyping

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Viruses have also been linked, with varying levels of speculation, to some forms of leukemia. Some forms of T-cell leukemia have recently been confirmed to be the result of two viruses. (See adult T-cell leukemia/lymphoma).

Related Topics:
Viruses - T-cell leukemia - Adult T-cell leukemia/lymphoma

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Radiation

In the early 1990s concern was raised in the UK about the effect of nuclear power plants on unborn children, when clusters of leukemia cases were discovered nearby to some of these plants. The effect was speculative because clusters were also found where no nuclear plants were present, and not all plants had clusters around them. Using statistical analysis, researchers at Southampton University concluded that a link was present, deducing that radiation damage to men working at the plants had caused genetic abnormalities in their children. After this report British Nuclear Fuels initially advised workers who were being exposed to high levels of radiation not to father children, although they have since withdrawn this advice.

Related Topics:
1990s - Nuclear power plant - Clusters of leukemia cases - Southampton University - British Nuclear Fuels - Radiation

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Immune system

In April 2005 the UK Childhood Cancer Study (UKCCS), a 15-year study tracking 11,000 children, including 1700 with leukemia, found problems relating to the immune system as a primary cause. In particular, around one in 20 children are born with slight genetic abnormalities which predispose them to leukemia, which appears to be triggered by an exaggerated immune response to infections. The study concluded that a significant factor in these exaggerated responses is children having a history of low exposure to infection - because the immune system was insufficiently trained in dealing with infection. The study found that increased levels of social activity outside the home reduced the risk of leukaemia, with the cut in risk greatest in children who attended formal daycare during their first three months of life. http://www.newscientist.com/article.ns?id=dn7301

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Electromagnetic fields

The UK Childhood Cancer Study (UKCCS) (see above) found no association between electromagnetic fields and the risk of childhood leukaemia http://www.newscientist.com/article.ns?id=dn7301.

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A large 2005 Oxford University

Related Topics:
2005 - Oxford University

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study

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did find a statistically significant elevation of childhood leukaemia rates (relative risk 1.7) within 200 m of high-voltage overhead power lines (132 to 400 kV),

Related Topics:
Overhead power lines - KV

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though the authors do not regard this as establishing a definite causal association

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http://www.hpa.org.uk/hpa/news/articles/press_releases/2005/050603_childhood_cancer_voltage.htm.

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A pooled analysis of case-control studies found that children living in homes with high magnetic fields (> 0.4 µT) had twice the risk of childhood leukaemia.

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Further research is needed, but a fair current assessment would be that electromagnetic fields produced by the electric power system are "possibly carcinogenic".

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