Case-control study on the use of cellular and cordless phones and the risk for malignant brain tumours

Purpose: To investigate the use of cellular and cordless phones and the risk for malignant brain tumours. Materials and methods: A case-control study was performed on 649 patients aged 20-80 years of both sexes with malignant brain tumour diagnosed from 1 January 1997 to 30 June 2000. All patients were alive during the time of the study and had histopathology verified brain tumours. One matched control to each case was selected from the Swedish Population Register. The study area was the Uppsala-Orebro, Stockholm, Linkoping and Goteborg medical regions of Sweden. Results: Exposure was assessed by a questionnaire answered by 588 (91%) cases and 581 (90%) controls. Phone usage was defined as 'ever use' and usage starting within 1 year before diagnosis was disregarded. Overall, no significantly increased risks were found: analogue cellular phones yielded an odds ratio (OR) = 1.13, 95% confidence interval (CI) = 0.82-1.57, digital cellular phones OR = 1.13, CI = 0.86-1.48, and cordless phones OR = 1.13, CI = 0.85-1.50. For ipsilateral (same side) radiofrequency exposure, analogue mobile phones gave OR = 1.85, CI = 1.16-2.96, for all malignant brain tumours. For astrocytoma, this risk was OR = 1.95, CI = 1.12-3.39. For all malignant brain tumours, digital mobile phones yielded OR= 1.59, CI = 1.05-2.41, and cordless phones yielded OR = 1.46, CI = 0.96-2.23, in the analysis of ipsilateral exposure. Conclusion: The ipsilateral use of an analogue cellular phone yielded a significantly increased risk for malignant brain tumours.