News

23rd April 2004

Day care could prevent childhood cancers

Sending your baby to day care during the first months of life could help protect them against childhood leukamia, according to the UK group, The Leukaemia Research Fund.

The study, carried out over the course of 10 years, found that early exposure to common infections helps to prime the immune system, whilst reduced exposure during the first year of life dramatically increases the risk of developing acute lymphoblastic leukaemia (ALL).

Acute lymphoblastic leukaemia (ALL) accounts for 85 per cent of childhood leukemias - cancer of the blood. The other 15 per cent is known as acute myeloid leukemia, or AML.

Childhood leukemias have been increasing at 1 per cent per year and many theories have been put forward as to the cause, such as environmental radiation.

However, the authors of the UK study, the biggest of its kind, say they now have compelling evidence that exposure to infections in infancy is key.

It looked at 6,305 children aged 2-14 years without cancer and 3,140 children with cancer, of whom 1,286 had ALL and questioned parents about day care during the first year of life.

The researchers found that increasing levels of social activity outside the home were linked to consistent reductions in the risk of ALL.

The greatest reduction in risk - of 52 per cent- was seen in children who attended formal day care on a regular basis during the first three months of life.

Those youngsters exposed to informal day care, such as that provided by friends and family, saw a 38 per cent drop in risk of ALL, while those who had some social activity, but not day care, had a 27 per cent lower risk.

Lead researcher Professor Mel Greaves, of the Institute of Cancer Research in London, said: "There is good biological evidence now that with childhood leukaemia, there is an interesting double whammy.

"First, there is a genetic mutation that occurs in the baby while they are in the womb, which happens very commonly."

"Then, in one per cent of those children, after birth, there is a trigger that causes a second mutation in the genes.

"There is abundant evidence now that the immune system requires infection in the first few months of life in order to be set up and function normally."

professor Greaves explained how if this does not happen, when the child is older and encounters an infection, that infection can then trigger the leukaemia.

"Infection early in life is good for you, it protects you - pretty much what your grandmother might have told you," he said.

Dr David Grant, scientific director of the Leukaemia Research Fund, which funded the research, said: "This is very reassuring for parents. We have had a lot of theories about what causes leukaemia, but this study takes us to a very firm conclusion.

"The more implausible theories I think we can now dismiss."

He added that treatments were improving and that now about 75 per cent of children with leukaemia survive the disease.

"But if we can prevent the disease occurring in the first place, which I think now is quite possible, then this has been a tremendously helpful study," he said.

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