British researchers suspect better living standards linked to childhood leukemia.
Leukemia cases among young British children are increasing and doctor's suspect improved living standards could be the cause.
Youngsters are exposed to fewer common infections than they used to be so their immune systems are weaker and not as good at combating illnesses, British researchers said on Friday.
Cases of acute lymphoblastic leukemia, the most common cancer in children, in northwest England rose dramatically from 1980 to 1998 and doctors believe the rise reflects increases across Britain. Most of the new cases were in children aged from one to four.
"We believe that it could be because youngsters' immune systems are becoming less good at warding off these infections," said Dr Richard McNally of the Royal Manchester Children's Hospital.
"And that could be because higher living standards mean children are not exposed to so much infection earlier in life and so their immunity is weaker," he added in a statement.
The theory that exposure to common infections early in life builds up the immune system is not new. Doctors also believe clean living is linked to dramatic rises in childhood asthma.
McNally and his colleagues have shown that the leukemia increases in Britain are limited to children under five which strengthens the hypothesis.
"This theory is consistent with data from developing countries where rates of all lymphoid leukemia, of which this type makes up roughly 80 percent, are far less common than in western countries," McNally added. The rate of the disease in young boys in Oxford in central England is nearly three times higher than in boys of a similar age living in Bombay, India. For young girls of the same age the Oxford rate is four times higher.
In a study published in The Lancet medical journal McNally and his team showed that the number of cases of the illness in northwest England increased about three percent a year in one-to-four year olds and the yearly rates increased more rapidly for girls than for boys.
Acute lymphoblastic leukemia is most common before the age of five and rare after the age of 25. It accounts for 85 percent of all childhood leukemia.
Improvements in treatment have increased remission and survival rates of the disease. Up to 60 percent of patients are cured.