Monday, April 25, 2005

Children who spend more time playing with other children are less likely to end up getting childhood cancers, a UK study published today in the British Medical Journal has found. The finding supports the researchers’ theory that reduced exposure to common infections in the first year of life increases the risk of developing acute lymphoblastic leukaemia (ALL).

A total of nearly 10,000 children took part in the study, located in 10 regions across the UK. Amount of time spent in daycare and social activity, during the first year of life, were used to gauge the level of exposure of the infants to common infections such as cold and flu.

Day care in the first year of life for at least two days a week, with at least three other kids, halved a child’s chance of contracting ALL. Those who were rated in the category “any social activity” still had an improvement over the children rated as “no social activity”: they had about 3/4 the chance of getting the disease.

The study describes that effect was “more striking” for acute lymphoblastic leukaemia — a cancer affecting blood and the immune system — than it was for the set of all other cancers. Increasing levels of activity saw decreasing chances of childhood cancers, when compared against children who during their first year had no regular social activity outside the home.

Theories have been around since the 1940s that childhood exposure to infection was related to the development of childhood leukaemia — one, like the working theory of the UK study, said that lack of immune challenge was a factor, another that leukaemia developed as a delayed result of some type of infection.

The research was conducted by the Institute of Cancer Research in London and in Sutton, London School of Hygiene and Tropical Medicine, University of York, Christie Hospital and Central Manchester and Manchester Children’s University Hospitals NHS Trusts, and the University of Edinburgh.