Acute Lymphoblastic Leukaemia (ALL) is a cancer of blood primarily affecting children. And currently kills around 1400 people a year in the USA alone. It is often a devastating disease, presenting with non-specific symptoms and can be advanced at the time of diagnosis. Treatment is usually chemotherapy, a collection of chemicals designed to wipe out cancer cells but often doing damage to other systems. For the longest time myriad causes have been used to explain the disease. But in a landmark article published in Nature Reviews Cancer, it may be that unifying cause has been found. And with it, new avenues for the prevention of this deadly disease.
A New Hypothesis
In his work, Professor Greaves reviewed 30 years of evidence, including studies on leukaemia ‘epidemics’ in the wake of infections, to come to the novel conclusion that ALL may be due to an ‘untrained immune system.’ He also noted that the rise of the disease in affluent societies (primarily western,) may be accounted for by this explanation. But to explain this new theory, we must first understand a little about the immune system.
The human immune system exists to identify, memorize and attack threats. These include viruses, bacteria and often atypical cells that could become cancer. In immunodeficient states, such as HIV, the immune system is rendered incapable of performing its tasks and people get sick with infections that otherwise would be harmless. You can be born with a faulty immune system, or it can become compromised later through disease, cancer or different therapies (chemotherapy, for example, can damage multiple systems including the immune.)
But a working immune system relies on exposure to a pathogen, like a virus, to be able to identify it, build up ways of fighting back and then, ultimately, attacking and destroying it. Failure at any part of this system creates problems. This is where ALL may be a problem. In his new Unified Theory, Greaves claims that the development of leukaemia happens like this:
- A genetic mutation occurs in the womb that increases the risk of developing a ‘pre-leukaemic’ clone cell.
- A lack of exposure to pathogens in the first year of development means that the immune system does not learn how to recognize and deal with threats.
- Exposure to infection later in childhood causes an immune misfire leading to leukaemia.
To put things simply, in a target population genetically predisposed to a higher risk of leukemia, reduced exposure to normal infections increases the risk of developing leukemia.
A Disease Of Affluence
This all may sound fairly straightforward, but you may wonder why western societies are at risk. Along with other hypotheses linking disease with sanitation, the Unified Theory suggests that our penchant for cleanliness may be a factor in creating disease. Often children in the western world, growing up in cities and with justifiably cautious parents, are simply not exposed to the same diseases that used to be commonplace. And then after an epidemic of a disease later, this means that the untrained immune system is prone to malfunction. It is a bold hypothesis but readily accounts for a disease that has a significant risk. As reported by the BBC, he said;
“The research strongly suggests that acute lymphoblastic leukaemia has a clear biological cause and is triggered by a variety of infections in predisposed children whose immune systems have not been properly primed.
But Greaves is quick to point out that there is no blame for parents, but that the disease more likely reflects society in general. He says it is not as simple as exposing your child to ‘dirt’, but that encouraging normal interactions with other children may be beneficial in early years. He also states categorically that more research is needed to establish how the disease can be prevented. And charity Bloodwise have been quick and sensible to reassure parents that nothing could have been done to prevent current cases based on Greave’s early findings. They said;
“While developing a strong immune system early in life may slightly further reduce risk, there is nothing that can be currently done to definitively prevent childhood leukaemia.”
Exposure and the Future
Whilst Greaves hypothesis may shed light on why ALL develops, it is just the start. For some kind of preventative measure to work we must first research further just what exactly is protective, and whether this can be delivered in a safe and reliable form. Something like a ‘live yoghurt’ has potential, but in a disease of such severity, we must be sure. This will take time. So although the research may provide new avenues, we must be patient to ensure that any new intervention will be effective.
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The opinions expressed in this article are those of Dr Janaway alone and may not represent those of his affiliates. If you are concerned about your health please see your local healthcare provider. Images courtesy of Flickr.