A major new analysis reveals for the first time the likely cause of most cases of childhood leukaemia, following more than a century of controversy about its origins.
Professor Mel Greaves from The Institute of Cancer Research, London, assessed the most comprehensive body of evidence ever collected on acute lymphoblastic leukaemia (ALL) - the most common type of childhood cancer.
His research concludes that the disease is caused through a two-step process of genetic mutation and exposure to infection that means it may be preventable with treatments to stimulate or 'prime' the immune system in infancy.
The first step involves a genetic mutation that occurs before birth in the foetus and predisposes children to leukaemia—but only 1 per cent of children born with this genetic change go on to develop the disease.
The second step is also crucial. The disease is triggered later, in childhood, by exposure to one or more common infections, but primarily in children who experienced 'clean' childhoods in the first year of life, without much interaction with other infants or older children.