Cellular telephones and risk of brain tumours

Abstract

In his review of epidemiological evidence on health risks of cellular telephones, Kenneth Rothman (Nov 25, p 1837)1Rothman KJ Epidemiological evidence on health risks of cellular telephones.Lancet. 2000; 356: 1837-1840Summary Full Text Full Text PDF PubMed Scopus (80) Google Scholar refers to our case-control study on brain tumours.2Hardell L Nasman A Palilson A Hallquist A Hansson Mild K Use of cellular phones and the risk for brain tumours: a case-control study.IntJ Oncol. 1999; 15: 113-116PubMed Google Scholar He refers to the questions by Ahlbom and Feychting3Ahlbom A Feychting M Use of cellular phones and the risk of brain tumours: a case-control study.Int J Oncol. 1999; 15: 1045PubMed Google Scholar on the inclusion of cases in this investigation. However, Rothman omits to mention that we simultaneously described in detail the inclusion of cases, and those fulfilling the inclusion criteria were included.4Hardell L Nasman A Palilson A Hallquist A Hansson Mild K Use of cellular phones and the risk for brain tumours: a case-control study.Int J Oncol. 1999; 15: 1045-1047PubMed Google Scholar In our study, 99 (50%) of 198 patients had tumours in the right brain, 78 in the left brain (39%) and 21 (11%) had central tumours.2Hardell L Nasman A Palilson A Hallquist A Hansson Mild K Use of cellular phones and the risk for brain tumours: a case-control study.IntJ Oncol. 1999; 15: 113-116PubMed Google Scholar These data were obtained from radiography reports. 57% of patients reported that they had mostly used telephones on the right ear, 28% the left ear, and 15% equally on right and left ears. Thus, we noted a predominance for the right side for brain tumours and the use of cellular telephones. In a further survey, of people reporting use of mostly the right ear or mostly left ear about 75% used only that particular ear. Of the remaining 25%, the largest proportion used the other ear for less than 10% of their calls. To assess use of cellular telephones, we did a multivariate analysis adjusting for other risk factors (laboratory work and medical diagnostic radiographic investigations of the head and neck). For brain tumours in the temporal, occipital, or temporoparietal areas (taken as exposed parts of the brain), the odds ratio was 2·62 (95% CI 1·02–6–71) for ipsilateral exposure. For contralateral exposure we calculated an odds ratio of 0·97 (0·36–2·59), and of 0·71 (0·14–3·68) for those reporting equal use of the right and left ears. Our results were, however, based on low numbers. Only 63 patients had tumours in these parts of the brain and odds ratios were based on 13 exposed cases. Given the low numbers, we recorded no increased risk for brain tumours overall. These results do not support Rothman's suggestion that telephone use does not affect the risk of whether a brain tumour will occur, only its location. This idea seems to be a new hypothesis in carcinogenesis and hard to follow. Cellular telephones and risk of brain tumoursAuthor's reply Full-Text PDF