Can childhood leukemia be prevented?

Can childhood leukemia be prevented? Going by resent findings that no exposure to common infections and away from other babies in the first year of life can trigger leukemia in children, scientists are hopeful that with properly primed immune system childhood leukemia may be preventable.

While there is the danger of keeping babies in ultra-clean environments, scientist Mel Greaves says that childhood leukemia might be preventable if a child’s immune system is properly ‘primed’ in the first year of life.

The study was revealed in a journal by researchers from the Institute of Cancer Research in the UK.

The research, which assessed the most comprehensive body of evidence ever collected on acute lymphoblastic leukemia (ALL), a cancer of blood-forming tissues, 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.

While the first step involves a genetic mutation that occurs in the foetus and predisposes children to leukemia, 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’ childhood in the first year of life, without much interaction with other infants or older children.

Acute lymphoblastic leukemia is particularly prevalent in advanced, affluent societies and is increasing in incidence at around one per cent per year.

Mel Greaves from the Institute of Cancer Research suggests that childhood ALL is a paradox of progress in modern societies - with lack of microbial exposure early in life resulting in immune system malfunction.

The study was published in the journal Nature Reviews Cancer.

For the study, Greaves compiled over 30 years of research into childhood leukemia. He challenged previous reports of possible environmental causes, such as ionising radiation, electricity cables, electromagnetic waves or human-made chemicals - arguing that none are supported by robust evidence as major causes.

Instead, he presented strong evidence for a ‘delayed infection’ theory for the cause of ALL, in which early infection is beneficial to prime the immune system, but later infection in the absence of earlier priming can trigger leukemia.

Childhood leukemia, in common with type I diabetes, other autoimmune diseases and allergies, might be preventable if a child’s immune system is properly ‘primed’ in the first year of life - potentially sparing children the trauma and life-long consequences of chemotherapy, said Greaves.

Population studies have found that early exposure to infection in infancy such as day care attendance and breast feeding can protect against ALL, most probably by priming the immune system. This suggests that childhood ALL may be preventable.

Greaves is now investigating whether earlier exposure to harmless ‘bugs’ could prevent leukemia in mice - with the possibility that it could be prevented in children through measures to expose them to common but benign microbes.

(With PTI inputs)