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Scientists at the University of Bern have analyzed the geographical distribution of cancer in children. The Zurich border area with Schaffhausen and Seeland stood out.
(sda)
Around 250 children and adolescents under the age of 16 develop cancer in Switzerland. It is the second leading cause of death in childhood in Switzerland and other European countries, as the research group led by the Institute for Social and Preventive Medicine (ISPM) at the University of Bern writes. Diseases in Switzerland have been recorded in the childhood cancer registry since 1976.
A small proportion of these cancers are genetic, the researchers wrote Thursday. “However, the cause of most illnesses remains unclear.” Environmental factors such as ionizing radiation (natural background radiation, medical diagnostic radiation), air pollution, electromagnetic fields, or pesticides are suspected.
“But the results of previous studies on these factors do not allow clear conclusions to be drawn,” explains Ben Spycher of ISPM, the study’s author. It was published in the “International Journal of Health Geographics”.
A plush toy in the intensive care unit of the Zurich children’s hospital.
Increasing exposure levels in certain areas can lead to a local increase in cancer risks. Model calculations by researchers from ISPM and the Swiss Group of Pediatric Oncology (SPOG) have found a slight increase in the risk of brain tumors in two regions of Switzerland: in the north of the canton of Zurich (border area with Schaffhausen) and in Zealand.
Search for environmental risk factors.
The following explanatory variables were used: degree of urbanization, socioeconomic position, air pollution related to traffic and natural background radiation. They were able to explain the spatial variability of the cancer rate as a whole, 72 percent, 81 and 82 percent for leukemia and lymphoma and 64 percent for brain tumors. However, it was not possible to use these variables to determine why brain tumors are particularly high in the two identified areas.
“We conclude that the search for environmental risk factors for brain tumors should be intensified,” says Spycher. Roland Ammann, co-author of the study at the Inselspital Bern University Pediatric Clinic, adds: “The different subgroups of brain tumors should also be considered separately.”
Corresponding group investigations are ongoing. “At this time we cannot say what might explain the differences observed in Switzerland, this needs to be further investigated,” says Spycher.
Brain tumors vary more geographically
The researchers examined the most common types of childhood cancer, namely leukemias, lymphomas, and tumors of the central nervous system (brain tumors). Overall, the analysis includes 5,947 cancers that occurred between 1985-2015. Of these, 1,880 (32 percent) were leukemias, 772 (13 percent) lymphomas, and 1,290 (22 percent) tumors of the brain and spinal cord.
For all cancers combined, the estimated local cancer rate deviated from the national average, depending on location, up to -17 percent less and up to +13 percent more. The spatial variation was less for leukemias (-4 to +9 percent) and lymphomas (-10 to +13 percent), but greater for brain tumors (-18 to +23 percent).
