Genetic mutation and infection 'most likely cause' of childhood leukaemia

The study by Bloodwise-funded researchers at The Institute of Cancer Research, London, published today in Nature Reviews Cancer, is the most comprehensive ever review of evidence on the causes of B-cell acute lymphoblastic leukaemia (ALL).

It concludes that risk of the disease is increased by a genetic mutation in the womb, and then about one per cent of children with the mutation go on to develop ALL as a result of their bodies responding to common infections in an abnormal way.

Given that the rate of ALL is slowly increasing, typical in high-income countries, Professor Greaves, Director of the Centre for Evolution and Cancer at The Institute of Cancer Research, London and author of the study, suggests that a lack of exposure to germs very early in life may result in the immune system malfunctioning (though it is likely that genetics and chance also play a role in the development of the disease).

Professor Greaves suggests this form of childhood leukaemia might be preventable if a child's immune system is properly ‘primed’ in the first year of life. He is now investigating whether earlier exposure to harmless bacteria could prevent leukaemia in mice – with the possibility that it could be prevented in children through measures to expose them to common but harmless bugs.

Professor Greaves, who has been funded by Bloodwise for 30 years, also concludes that theories that electricity cables, electromagnetic waves or man-made chemicals increase risk of ALL are not supported by the evidence.

The study looked at ALL, which accounts for about 400 out of the 500 children in the UK who develop leukaemia every year. The causes of other forms of childhood leukaemia are likely to be different.

Professor Greaves said: “This body of research is a culmination of decades of work, and I hope it will have a real impact on the lives of children. The most important implication is that most cases of childhood leukaemia are likely to be preventable. It might be done in the same way that is currently under consideration for autoimmune disease or allergies – perhaps with simple and safe interventions to expose infants to a variety of common and harmless ‘bugs’.”

Dr Alasdair Rankin, Director of Research at Bloodwise, said: “Current treatments for childhood leukaemia are not always successful, and even when they are, can have severe short and long-term side effects, so research to find kinder treatments is very important. If we could stop this type of leukaemia from happening in the first place it would be enormously exciting, but many more questions still need to be answered in the research lab before we will know for sure whether that could become a reality.

“We urge parents not to be alarmed by this study – childhood leukaemia is rare and only around one in 2,000 children will develop it. While developing a strong immune system early in life may further reduce risk, there is nothing that can be currently done to definitively prevent childhood leukaemia. As noted by this study, other factors influence its development - including pure chance.”

Read our Director of Research's response to this exciting news.

Related story: Mel Greaves wins prestigious Royal Society award.