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, a new study finds, CNN reports.

Cancer could be preventable, suggests the author Institute of Cancer Research Professor Mel Greaves.

Results were published in the journal Nature Reviews Cancer.

Germ-free childhood

Acute lymphoblastic leukemia (ALL), the most common type of childhood cancer, is caused by a two-step process the study suggests.

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.

Germ-free childhoods followed by infections later in life can trigger the onset of childhood leukemia, the new study suggests.

Clear biological cause for cancer

This body of research is a culmination of decades of work, and at last provides a credible explanation for how the major type of childhood leukaemia develops," the author wrote in a statement. "The research strongly suggests that (this cancer) has a clear biological cause, and is triggered by a variety of infections in predisposed children whose immune systems have not been properly primed."

Epidemiological and modelling studies endorse a dual role for common

infections. Microbial exposures earlier in life are protective but, in their absence, later infections trigger the critical secondary mutations. Risk is further modified by inherited genetics, chance and, probably , diet.

Childhood ALL can be viewed as a paradoxical consequence of progress in modern societies, where behavioural changes have restrained early microbial exposure. This engenders an evolutionary mismatch between historical adaptations of the immune system and contemporary lifestyles. Childhood ALL may be a preventable cancer", writeas the author.

Read the whole study HERE