Research published in the International Journal of Health Geographics aims to explain the role that geography plays in pediatric cancer diagnoses. While genetics does play into childhood cancer, it is not as influential as some may think. This begs the question - if not nature, what part of nurture is affecting these children?
This study was conducted on children with pediatric cancer in Switzerland, where about 250 children are diagnosed with cancer annually. Several environmental factors are thought to potentially play a role in their diagnoses, including ionizing radiation (natural background radiation, medical diagnostic radiation), air pollution, electromagnetic fields or pesticides, but as one author of the study points out, these are merely speculations.
"The results of previous studies of these factors do not allow us to draw any firm conclusions" explains Ben Spycher of the Institute of Social and Preventive Medicine at the University of Bern, the last author of the study.
Spycher and his fellow researchers at the ISPM and Swiss Paediatric Oncology Group SPOG utilized data from Switzerland’s national Childhood Cancer Registry which holds records dating back to 1976. They used statistical models indicating the children’s home addresses, ages, and diagnoses to determine if increased exposure levels in certain areas correlate with locally increased cancer risks.
They found that indeed, in two regions of the country, there is a slight increase in the risk of brain tumors. The two regions with an increased incidence of brain tumors were in the north of the canton of Zurich (border area with the canton of Schaffhausen) and in the Seeland. "Further analyses showed that the risk increase mainly concerns the group of embryonal brain tumors," says co-author Roland Ammann, from the University Clinic for Pediatrics at the Inselspital, University Hospital of Bern.
While the researchers considered the influence of urbanization, socio-economic position, and environmental factors (nitrogen dioxide concentration and natural background radiation), these factors only partially explained the spatial variability of the cancer rate and did not explain the increased rates of brain tumors seen in the two aforementioned regions.
"We conclude that the search for environmental risk factors of brain tumors should be intensified," says Spycher. Roland Ammann adds: "The various subgroups of brain tumors should be considered separately. At this stage, we cannot say what might explain the observed differences in Switzerland, this needs to be further investigated," says Spycher.