Cancer is more likely in children from rich, rural British families
Authors: Andrew Cole
Journal: BMJ (2006)

Children from affluent backgrounds who live in rural or isolated areas in England, Wales, and Scotland are more likely than other children to develop cancer, says the largest ever survey of childhood cancer in Britain.

It dismisses the suggestion that radiation from nuclear power stations is responsible for any increase in the incidence of childhood cancer, but it does propose that research be conducted into the clusters of cancer around Sellafield in Cumbria and Dounreay in Scotland.

The Committee on Medical Aspects of Radiation in the Environment, an independent expert advisory committee, looked at more than 32 000 cases of cancer in children under the age of 15 between 1969 and 1993.

It found that the prevalence of cancer was very unevenly distributed. In particular, childhood leukaemia, cancers of the central nervous system, bone tumours, and some lymphomas were more common in affluent areas and areas of low population density. The overall prevalence of cancer among children in the top socioeconomic group was 126.4 cases per million, whereas in the most deprived group it was 103.1 per million.

However, Hodgkin’s lymphoma showed a different pattern, a higher prevalence being associated with greater population density and greater social deprivation.

The committee found that many cancers—especially acute lymphoblastic leukaemia, soft tissue sarcomas, and osteoscarcoma—tended to cluster in particular areas and that these clusters lasted just a few years.

Also, cancer prevalence varied widely across the country. Buckinghamshire had 132.2 cases of childhood cancer per million, 40% higher than the prevalence in West Glamorgan (94.1 cases per million). Cambridgeshire had a very high prevalence of bone tumours (8.8 per million), while the areas with the highest prevalence of renal tumours were Borders (14 per million) and Western Islands (13 per million) in Scotland and Cornwall and Wiltshire in England (11 per million).

The committee’s chairman, Alex Elliott, said that the correlation between leukaemia and socioeconomic status had been known but that the link with many other childhood cancers was new and indicated that the cancers might have common causes.

Together with the tendency of many cancers to cluster, this lent weight to the theory that a virus might be partly responsible. “That doesn’t mean that one child catches cancer from another,” Professor Elliott said, “but there could be an underlying process that triggers the condition later.”

This scenario opens up the possibility of developing a vaccine. “If you believe theories that development of childhood cancer involves multiple steps and one of them is caused by a virus, and if you can identify that virus, it might be possible to develop a vaccine against it and break that causative chain,” he said.

One possible explanation for the disproportionate prevalence of childhood cancer in richer, more rural areas is “population mixing,” said Professor Elliott. This theory has it that an influx of newcomers into a relatively isolated area can trigger an increase in infections—and in rare cases leukaemia—because the native group has poorer immunity.

The committee found some evidence of a higher risk of childhood cancers close to the nuclear installation at Rosyth in Scotland. This requires further research, it says.

The Distribution of Childhood Leukaemia and other Childhood Cancers in Great Britain 1969-1993 is available at www.comare.org.uk.