Why a cold, other infections may induce childhood leukemia (subgroup)

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Why a cold could set off childhood leukaemia

By Nic Fleming, Science Correspondent

(Filed: 13/12/2005)

http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2005/12/13/ncold13.xml

& sSheet=/news/2005/12/13/ixhome.html

Infections such as the common cold could play a significant role in

triggering childhood cancers, according to a study.

The discovery of linked clusters of leukaemia and brain tumours in

children suggest many cases could be caused by a combination of genetic

susceptibility and common contagious illnesses such as colds, measles and

flu viruses.

The findings support previous research showing young children who are

socially active, such as those who attend nurseries, are less at risk than

those who are more sheltered because they develop stronger immune systems.

Dr McNally, an epidemiologist at Newcastle University and the

study's lead author, said: " The patterns we observed suggest that the

cause may be linked to diseases passed from person to person.

" These findings are consistent with previous studies that have shown that

delayed exposure to infections probably leads to an increased risk of

leukaemia and, for the first time, suggests it may also increase the risk

of brain tumours. "

Dr McNally and colleagues analysed records of all cancers in children aged

up to 14 years old diagnosed between January 1954 and December 1998 in

southern Cumbria, Lancashire, Greater Manchester, north-west Derbyshire

and north Cheshire. The total number of cases was around 5,000.

They found leukaemia and brain tumours repeatedly occurred at similar

times and geographical locations in a " space-time clustering " of cases

that is a pattern typical of diseases caused by infection.

A whole range of environmental factors for childhood cancers have been

suggested - such as power lines, pollution and nuclear waste.

However, such potential causes would be expected to produce specific

clusters over longer periods.

Analysis of patterns of childhood leukaemia and brain tumours suggested

that eight per cent of cases were likely to be linked with the spread of

infectious diseases.

The link was strongest between acute lymphoblastic leukaemia and

astrocytoma brain tumours, for which 13 per cent of cases appeared linked.

The association was strongest when increased rates of the childhood

cancers were compared with time and place of birth, rather than time and

place of diagnosis.

Dr McNally said: " We found that place of birth was particularly

significant, which suggests that an infection in the mother while she is

carrying her baby, or in a child's early years, could be a trigger factor

for the cancer.

" These could be minor, common illnesses that are not even reported to the

GP, such as a cold, mild flu or a respiratory virus.

" However, this would only lead to cancer in individuals who already carry

mutant cells in their body. The virus would hit this mutant cell and cause

a second mutation, prompting the onset of cancers like leukaemia or brain

tumours. "

He added that his team's research was unable to pinpoint which specific

infectious illnesses might trigger the development of the cancers.

The findings, published in the European Journal of Cancer, could lead to

better prevention measures and improved treatment.

*

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