Childhood cancer is very rare — but not as rare as it used to be.
New figures show rates have increased by 40% over the last 16 years in Britain.
It’s a worrying trend, not least because it’s unclear why it’s happening.
However, it’s thought a significant proportion of the extra cases may be linked to changes in lifestyle and environment, for both children and parents.
The International Agency for Research on Cancer (IARC), part of the World Health Organisation, has classified outdoor air pollution as a cancer-causing agent, saying it causes lung cancer and is linked to bladder cancer.
“The air we breathe is filled with cancer-causing substances,” says Dr Kurt Straif of the IARC.
“Outdoor air pollution is not only a major environmental risk to health in general, it is the most important environmental cancer killer, due to the large number of people exposed.”
The main artificial sources of outdoor air pollution are transportation, stationary power generation, industrial and agricultural emissions, and residential heating and cooking, notes the IARC.
Professor Denis Henshaw, a specialist in children’s cancer believes around 30% of childhood cancer in urban areas is linked with air pollution.
In 2014, the Childhood Leukaemia International Consortium (CLIC) found that when parents are exposed to pesticides during pregnancy or conception, there was an increased risk of leukaemia for their child.
This risk applies to both the mother and the father, whose sperm may be affected.
Radiation is known to increase cancer risk in children and adults, and children who have radiotherapy for cancer have a slightly increased risk of developing another cancer later.
Henshaw says data suggests 5% of childhood leukaemia is linked to radon, a radioactive gas found naturally in the ground.
It diffuses into open air and isn’t a health hazard outside, but a house can trap radon gas.
However, researchers say studies show there may only be a weak link between indoor levels of radon gas and the risk of childhood leukaemia.
The IARC classes electromagnetic fields (EMF), of the type associated with our electricity supply, as ‘possibly carcinogenic’ to humans, based on studies that reported an approximate doubling of leukaemia risk for children exposed at average levels above 0.3 – 0.4 microtesla.
However, no conclusive link has been found between EMF and cancer.
Studies suggest carcinogens from a mother’s diet can cross the placenta into an unborn baby’s bloodstream, and Henshaw, says some of the carcinogens could come from processed meats and burned barbecue meats eaten by pregnant women.
Eating a healthy diet full of fruit and vegetables is important for all the family, including pregnant women and children, says Henshaw.
In addition, an Australian study found mothers who took folate and iron supplements during pregnancy had more than a 60% reduced risk of their children developing leukaemia.
Sending children to day care in infancy may have a protective effect against leukaemia, too.
“The theory is that children are exposed to common infections from mixing with other children, and this strengthens their immune system,” explains Henshaw.