Case-Control Study on Radiology Work, Medical X-ray Investigations, and Use of Cellular Telephones as Risk Factors for Brain Tumors

, Department of Oncology, Orebro Medical Center, SE-701 85 Orebro, Sweden email: , Department of Oncology, Orebro Medical Center, SE-701 85 Orebro, Sweden , Department of Neurology, Orebro Medical Center, SE-701 85 Orebro, Sweden , Department of Oncology, Karolinska Institute and Stockholms Sjukhem, Mariebergsgatan 22, SE-112 35 Stockholm, Sweden

In This Article

Materials and Methods

This study is our first investigation on this topic and will be followed by a much larger study, which is currently in progress. The aim is to test both the feasibility of studying this patient group and some specific etiologic hypotheses, including the use of cellular telephones. When the study started in the Uppsala-Orebro medical region of Sweden, only patients with a malignant brain tumor diagnosed in 1994-1996 were included. Furthermore, they had to have had a histopathologic diagnosis available according to the Cancer Registry at the time of operation and been alive at the study start. The physicians were contacted for permission to include the patient in the study. Two controls to each case were drawn from the population register. They were matched for sex and age and lived in the same geographic area of Sweden as the cases.

To include a larger study area, the Stockholm medical region was included for the study period (1995-1996). Only patients with a malignant brain tumor were included initially. The same procedure for assessment of exposure was used as in the Uppsala-Orebro region.

The World Health Organization (WHO) contacted us in 1997 regarding a study of exposure to cellular telephones and the risk of brain tumors, which we agreed to participate in. WHO decided to start with a feasibility study, and our ongoing study on brain tumors was included as part of that study.[7] However, benign brain tumors were also included in the WHO feasibility study. Thus, in our study we included patients with benign brain tumors who were living in the Stockholm medical area, since assessment of data was still ongoing in that part of the investigation. Therefore, assessment of exposure was obtained for patients with both malignant and benign brain tumors during the same period. However, we included only patients with benign brain tumors diagnosed in 1996 to fulfill the time criteria for the feasibility study.[6,7] The study method was the same in the whole investigation.


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