Childhood cancer rates rise in Europe

Cancer rates among children have been rising in the UK and Europe over the last 30 years, research has revealed.

While childhood cancer is rare, the overall incidence has increased by 1% a year since the 1970s, and 1.5% a year for adolescents, scientists from the International Agency for Research on Cancer (IARC) in Lyon, France, say in research published today in the medical journal Lancet.

Data was collected from 19 countries because the small number of cases in each made it harder to see trends.

But the scientists said that when the data was grouped together it was clear the numbers were going up, although there were some differences between western and eastern Europe and some variations in age groups.

"Perhaps the most striking result is the clear evidence of an increase of cancer incidence in childhood and adolescence during past decades and of the acceleration in this trend," they write.

More difficult is to point to the possible causes. "It is a very difficult question to answer," said Eva Steliarova-Foucher from IARC.

"We can speculate from the results of other studies that there might be changes in childbearing which might affect the changes in the incidence of cancer."

Some research had shown an association between higher birth weight and leukaemia, she said.

But there are many other possibilities. Research in the UK has suggested that viral infections brought in to communities when populations move might be a trigger, she said.

And while many people assumed that pollution was a factor, studies of the possible exposure to hydrocarbons of children with brain tumours found no conclusive evidence.

She hoped that the epidemiological evidence they had found would help the research into causes.

The IARC study showed a rise in childhood cancers from 118 per million in the 1970s to 124 in the 1980s to 139 in the 1990s.

While there have been improvements in diagnosis, these did not account for the scale of the increase. The study also revealed that the rise had accelerated. The annual change was less than 1% between the 1970s and 1980s, but 1.3% between the 1980s and 1990s.

There were some differences in the rates between the west and east of Europe, but significant blips could often be accounted for. The high rate of cancer in children in the east in the 1990s was due to 603 thyroid cancer cases in Belarus. Without those, the overall rate in the east dropped below that in the west.

"Therefore the excess rate in children in the east can probably be entirely attributed to the Chernobyl incident in 1986," the study said.

Some cancers in specific population groups needed to be investigated to try to find the reason.

"The most obvious target for further research is the peak of lymphoid leukaemias in early childhood which has been recorded in England and Wales and in the USA since the first half of the 20th century," they wrote.

These leukaemias peak at around the age of two, and seem to be more common in more affluent families.

Because of improved treatment more children were surviving cancer, although the rate of improvement in survival was greater in the west than in the east.

In the west, 75% of children and adolescents survived for at least five years, compared with 64% in the east. In the west, the authors said, children were likely to be taken to a doctor and referred to a consultant earlier and complex treatments were more often available.

In a commentary in Lancet, Catherine Cole, a child cancer expert from Perth, Australia, said that as diagnosis and the collection of data on child cancer cases improved, the numbers would go up. It would be some time before it became clear whether there really was an underlying rise in cases.

Most children with cancer were in the developing world and most would die for want of medical care.