Acute lymphoblastic leukaemia (ALL) is described as a childhood “disease of affluence”. It is virtually unknown in developing countries but is increasing in incidence in the developed. Various explanations have been put forward for this correlation, including magnetic fields generated by overhead power transmission cables. A new study draws together the evidence which has given strong evidence as to why children develop the disease and a way of preventing it. That could be as simple as a yoghurt type drink.
Prof Greaves - who has collaborated with researchers around the world - says there are three stages to the disease.
- The first is a seemingly unstoppable genetic mutation that happens inside the womb
- Then a lack of exposure to microbes in the first year of life fails to teach the immune system to deal with threats correctly
- This sets the stage for an infection to come along in childhood, cause an immune malfunction and leukaemia
This "unified theory" of leukaemia was not the result of a single study, rather a jigsaw puzzle of evidence that established the cause of the disease.
Prof Greaves 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."
Obviously nothing can be done to change the genetic pre-disposition to the cancer although it may be very possible to identify those at risk by DNA testing. What can be addressed is the lackof exposure to microbes in the first year. The evidence for this also points to ways of preventing the leukaemia developing.
- Its incidence is lower in those children born vaginally;
- Its incidence is lower in children who have been breastfed.
- Its incidence is lower in children with older siblings or who have gone to nurseries.
All three expose children to micro-organisms. (There is also increasing evidence that gut bioflora play an important part in maintaining health, including weight regulation. Studies if identical twins show that if one is significantly heavier, they have less diverse stomach bioflora.)
Caesarian births are obvious necessities for some women however the World Health Organisation put the number needed at about 10% — 15% of live births. They have however increased far beyond that in affluent countries.
The rate of caesarean section births in the U.S. was 32.7 percent in 2013 -- well above the “medically necessary” target of 10 percent to 15 percent that WHO says is ideal. Germany and Italy have similarly high rates -- 32 percent and 38 percent, respectively -- while low-income countries like Afghanistan and Kenya hadn't yet reached 10 percent, according to data from 2011. Brazil, notorious for high caesarean rates, tops the list at 52 percent.
At the same time, new cases of ALL have shown a slight but significant increase. This study gives more weight to the argument against the use of caesarian sections routinely — or even to suit the doctors’ schedules. It certainly shows that natural childbirth and breast feeding should be encouraged as far as possible. The research does however point a way forward.
Prof Greaves adds: "The most important implication is that most cases of childhood leukaemia are likely to be preventable."
His vision is giving children a safe cocktail of bacteria - such as in a yoghurt drink - that will help train their immune system.
This idea will still take further research.
In the meantime, Prof Greaves said parents could "be less fussy about common or trivial infections and encourage social contact with other and older children".
While incidence of the disease is low (but rising), the obvious remedies have significant effects even if the child is at no genetic risk. Caesarian births pose risks for both mother and child.
American College of Obstetricians and Gynecologists recently released a statement indicating that there are about 13 deaths for every 100,000 women after C-sections. There only about 4 deaths for every 100,000 women after a vaginal delivery. For the past few decades, while the rest of the world has reduced the number of mothers who died during childbirth by about a third, maternal mortality rates have nearly doubled in the U.S. In addition, instances where a woman has complications from childbirth so severe that she nearly dies are up 27 percent in the U.S.
Add to that the cost of the delivery, either for the patient or the healthcare system and there are obvious benefits, in terms of health and finances, of a strategy to reduce the number. While this and the other measures could not eliminate the risk for an individual child, they anyway provide a raft of benefits. Other studies suggest that lack of exposure to various factors, e.g. peanuts, early in life can cause allergies in children.