Over 30 years of research has determined that acute lymphoblastic leukemia (ALL), the most common cause of cancer in children, could actually be prevented in a very simple way. Scientists believe that our obsession with cleanliness and fear of germs could actually play a role in the disease by stopping children’s immune systems from developing properly.
ALL is a type of blood cancer that affects the bone marrow. While it is most common in those aged 4 and younger, it can affect adults too, with about 6,000 Americans being diagnosed each year. Today about 90 percent of children with ALL are cured, although the treatments are unpleasant to endure. The discovery that the disease might be preventable is very exciting news.
Looking at a wide range of previous studies, and publishing their results in Nature Reviews Cancer, the researchers came up with the following theory for how too much cleanliness could lead to the disease.
About one in 20 children have a genetic predisposition to ALL, but if their immune system develops properly, they will remain healthy. However, if they’re not exposed to plenty of microbes in the first year of life, their immune system won’t develop as well and won’t know how to cope with infection. This is why cleanliness has actually been linked to the development of allergies.
Then, if a child with the genetic predisposition and a poorly developed immune system gets infected with something like a cold or the flu later on, a second genetic mutation can appear. This is what makes the child more likely to become sick with ALL. It doesn’t mean they’ll definitely get it, but it can make them more susceptible.
Our modern lifestyles mean that we often keep everything squeaky clean, and intentionally protect our children from any potential germs. But oddly enough this isn’t actually a good thing. Our bodies are naturally meant to come into contact with all sorts of dirt and bugs when we’re growing up, as it’s what makes our immune systems good at dealing with unpleasant germs.
Therefore, as a child, lots of interaction with other kids, having pets, or playing in the dirt can actually be very beneficial to your health. But if you spent your childhood in a super-clean environment, you’re much more likely to suffer from asthma and allergies. You’re even at a higher risk of autoimmune diseases like type 1 diabetes and multiple sclerosis (MS). Our super-clean lifestyle is thought to be the reason why these conditions have skyrocketed in recent decades – but only in developed countries. Less developed nations who are exposed to more germs have not seen this dramatic rise.
“Infectious disease tracks with poverty,” first author Professor Mel Greaves, a leading cancer scientist, told The Guardian. “The problem is not infection. The problem is lack of infection.”
Nevertheless, as with most things, there probably isn't one sole culprit, so while cleanliness might contribute, it probably isn't the only cause. In terms of ALL, genetic predisposition and chance also play a role, and the researchers point out that parents of those with ALL should not feel responsible.
Still the findings could certainly help us combat the disease in future, and the researchers now plan to work on preventative treatments for ALL.