[ RadSafe ] Radiation, chemicals and power lines are not significant in childhood leukemia

[John Jacobus]

Another interesting article at
http://www.nature.com/nature/journal/v434/n7037/full/4341058b.html

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News
Nature 434, 1058 (28 April 2005) 

Link to infection raises hope of preventing child
leukaemia

Roxanne Khamsi, London

Radiation, chemicals and power lines are not
significant.

It is finally possible to identify the environmental
factors responsible for childhood leukaemia,
researchers told a meeting in London last week. Now
it's time to think about how to prevent the disease,
they said.

Exposure to radiation, chemicals and power lines are
not a significant cause, the meeting heard. In fact,
most cases are caused by common infections in
toddlers.

Leukaemia causes the production of abnormal white
blood cells, and accounts for a third of cancers in
children. Some genetic predisposition is involved, but
for decades scientists have been trying to identify
what triggers the disease.

The biggest effort is the United Kingdom Childhood
Cancer Study, set up in 1991. It compiled information
from more than 10,000 children, including some 1,700
with leukaemia.

Researchers from the project met last week to discuss
the results. They were agreed on the role of chemicals
and radiation. "Perceived risk factors such as living
near sources of electromagnetic fields or natural
radiation are not principal causes, if at all, of
leukaemia in children," says Mel Greaves of the
Institute of Cancer Research in London.

Infections, on the other hand, induce a proliferation
of white blood cells in bone marrow as part of the
normal immune response. In children genetically
predisposed to leukaemia, the researchers think that
infection might cause an uncontrolled proliferation of
cells, leading to cancer.

Although several studies have hinted that infection
could be a cause, it has taken the size and
statistical power of the UK project to convince
researchers that there really is a significant link.
To do this, epidemiologist Eve Roman of the University
of York and her team analysed data on children's
day-care attendance.

Records from East Germany had hinted that infants sent
to playgroups from the age of three months were less
likely to contract leukaemia. So Roman's team set out
to test whether exposure to infections very early in
life could somehow train the immune system to protect
against the cancer.

They focused on acute lymphoblastic leukaemia, a
common form of the disease that usually strikes
between the ages of two and five — the time most
children start going to playgroups. The team found
that children who attended day care during the first
three months of life had half the normal risk of
developing the disease (C. Gilham et al. Br. Med. J.
doi:10.1136/bmj. 38428.521042.8F; 2005).

Attention is now turning to how to prevent leukaemia.
Encouraging parents to send their children to
playgroups early in life is one obvious option.
Identifying the infections responsible also raises the
possibility of developing protective vaccines. Greaves
notes that US and Finnish studies have suggested that
the Hib vaccine against meningitis also helps to
protect against leukaemia.

Charles Stiller, a cancer epidemiologist at the
University of Oxford, UK, is excited about the shift
but cautions against getting too carried away. "It's
difficult to know what proportion of cases is
accounted for by infections," he says. "And there is
more to be done on defining the mechanisms by which
this might work."

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"Embarrassed, obscure and feeble sentences are generally, if not always, the result of embarrassed, obscure and feeble thought."
Hugh Blair, 1783

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com

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