Global childhood cancer rates jumped 13 percent in the decade to 2010 compared to the 1980s, according to a UN-backed study released Wednesday that says the increase may be due in part to improved detection.
For children under 15, the incidence rate of cancer was 140 per million during the first decade of this century, the International Agency for Research on Cancer (IARC) reported in The Lancet Oncology.
Part of the increase compared to the 1980-1990 period "may be due to better, or earlier, detection or these cancers," the agency said in a statement.
Data collected on 300,000 cancer cases diagnosed in 2001-2010 showed that leukaemia accounted for nearly a third of childhood cancers, followed by tumours of the central nervous system (20 percent) and lymphomas (12 percent).
In children under five, a third of cases were embryonal tumours, such as neuroblastoma.
Incidence among adolescents 15 to 19 years old over the same decade was 185 per million.
"Cancer is a significant cause of death in children and adolescents, in spite of its relatively rare occurence," compared to adult cancer rates, said IARC Director Christopher Wild.
Cancers in children are more likely to be triggered by genetic factors.
The report makes no attempt to determine what portion of the reported increase in incidence is due to better diagnoses, or other factors such as infections and pollution.
Data for the study came from 153 cancer registries in 62 countries, departments and territories representing about 10 percent of the world's children.
But coverage was very uneven: nearly 100 percent of the child population in the North America and Europe was included, but only five percent or less for children in Africa and Asia.
In low-income countries, data collection is difficult due to under-funded health systems and statistical services.
"Often focusing on the small proportion of cancers occurring in children is not seen as a priority," the IARC said in a statement.