The overall incidence of childhood cancer in Europe has been rising at a rate of 1.1% a year on average, a new study shows.
Figure 1.
The researchers found that from 1978 to 1997 the age standardised incidence increased from 120 cases per million children to 141 (European Journal of Cancer 2006:42; 1961-116919764).
Although the rise may be partly the result of changes in diagnosis and registration of cases, the authors say that the size of the increase and other factors point to other causes.
“The patterns and magnitude of these increases suggest that other factors—for example, changes in lifestyle and in exposure to a variety of agents, have contributed to the increase in childhood cancer in the recent decades,” write the authors, from the University of Mainz, the International Agency for Research on Cancer, and other centres.
The researchers used data from the automated childhood cancer information system project to look at trends in the incidence of cancer in children from 1978 to 1997. The data came from 33 cancer registries in 15 European countries and involved almost 80 000 cases.
Their results show that over the 20 year period the incidence increased by an average of 1.1% a year and that in each five year period the incidence was higher than in the preceding one. The trend was seen in all geographical areas and in most of the disease groups, ranging from an average rise of 1.8% a year for soft tissue sarcomas to 0.6% for leukaemias. No change was seen in the incidence of bone tumours, hepatic tumours, and retinoblastoma.
The authors point out that the average increase was greater among girls than boys, although the baseline cancer incidence was higher among boys.
The authors say there are probably many possible risk factors that are not well understood. Possibilities include increased mobility; changing exposure to a variety of artificial and natural agents; changes in lifestyle; maternal diet; and reproductive history, pregnancy, and perinatal factors.
“Changes in genetic factors cannot be excluded, due to improved medical care, which allows affected individuals reaching the reproductive age and possibly transferring predisposition to certain cancers,” the authors wrote.