(CNN)Germ-free childhoods followed by infections later in life can trigger the onset of childhood leukemia, a new study suggests.
The paper, published Monday in the journal Nature Reviews Cancer, finds that acute lymphoblastic leukemia, the most common type of childhood cancer, is caused by a two-step process.
The first step is a genetic mutation before birth that predisposes a child to the risk of developing this form of leukemia. The second step is exposure to certain infections later in childhood, after clean early childhoods that limited exposure to infections.
More specifically, children who grew up in cleaner households during their first year and interacted less with other children are more likely to develop acute lymphoblastic leukemia, the paper says.
The author, Institute of Cancer Research Professor Mel Greaves, suggests the cancer could be preventable.