Our modern germ-free life is the cause of the most common type of cancer in children, according to one of Britain's most eminent scientists. Professor Mel Greaves of the Cancer Research Institute has accumulated 30 years of tests to show that the immune system can become cancerous if it does not "see" enough "bugs" at a young age. The type of blood cancer is more common in advanced and prosperous societies, suggesting that something about our modern lives may be causing the disease.
There have been crazy claims that link power cords, electromagnetic waves and chemicals with cancer. That has been ruled out in this work published in Nature Reviews Cancer. Instead, Professor Greaves, who has collaborated with researchers around the world, says there are three stages of the disease. The first is a seemingly unstoppable genetic mutation that occurs within the uterus. Then, the lack of exposure to microbes in the first year of life does not teach the immune system to handle threats correctly. This sets the stage for an infection that appears in childhood, causes a malfunction of the immune system and leukemia.
This "unified theory" of leukemia was not the result of a single study, but a puzzle of evidence that established the cause of the disease. Professor Greaves said: "Research strongly suggests that acute lymphoblastic leukemia has a clear biological cause and is triggered by a variety of infections in predisposed children whose immune system has not been properly prepared."
The evidence that helped build the case included:
- An outbreak of swine flu in Milan that led to seven children contracting leukemia.
- Studies that show that children who went to daycare or had older siblings, who exposed them to bacteria, had lower rates of leukemia.
- Breastfeeding - which promotes good bacteria in the intestine - protects against leukemia.
- Lower rates in children born vaginally than by cesarean section, which transfers less microbes.
This study does not pretend to blame the parents for being too hygienic. Rather, it shows that a price is being paid for the progress we are making in society and medicine. Getting into contact with beneficial bacteria is complicated, it is not just about embracing dirt. But Professor Greaves adds: "The most important implication is that most cases of childhood leukemia can be prevented."
His vision is to provide children with a safe cocktail of bacteria, such as a yogurt drink, which will help train their immune system. This idea will still require more investigation. Meanwhile, Professor Greaves said parents could "be less fussy about common or trivial infections and foster social contact with other children and adults."
Dr. Alasdair Rankin, research director at the Bloodwise charity, said: "We urge parents not to be alarmed by this study." While the development of a strong immune system early in life may reduce the risk a little more , there is nothing that can be done at present to definitively prevent childhood leukemia. "
This study is part of a massive change that takes place in medicine. To date, we have treated microbes as bad ones. However, recognizing its important role for our health and well-being is revolutionizing the understanding of diseases, from allergies to Parkinson's and depression, and now leukemia. Prof. Charles Swanton, clinical head of Cancer Research UK, said: "Childhood leukemia is rare and nowadays it is not known what can be done to prevent it, either from medical professionals or from parents." We want to assure the parents of a child who has or has had leukemia, that there is nothing we know that could have been done to prevent their disease. "