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• What can be learned from the Japanese study of mobile phone use and acoustic neuroma?
  Michael Kundi
  Published on: 14 May 2007

• Published on: 14 May 2007

  What can be learned from the Japanese study of mobile phone use and acoustic neuroma?

  • Michael Kundi, Univ.Prof.

  The Japanese case-control study of acoustic neuroma and mobile phone use (Takebayashi et al. (1)) although thoroughly conduced and analysed has still some important limitations. Acoustic neuroma have long latencies (2, 3). Results of 16 studies published between 1985 and 2000 (4) demonstrated tumour growth in 48-70% of patients, stable tumour volumes in 27-50% and involution in 2-10%. The reason for the diverse patterns of...

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  The Japanese case-control study of acoustic neuroma and mobile phone use (Takebayashi et al. (1)) although thoroughly conduced and analysed has still some important limitations. Acoustic neuroma have long latencies (2, 3). Results of 16 studies published between 1985 and 2000 (4) demonstrated tumour growth in 48-70% of patients, stable tumour volumes in 27-50% and involution in 2-10%. The reason for the diverse patterns of schwannoma growth is largely unknown. If exposure to microwaves from mobile phones has an influence on growth rate this might result in [1] restart of growth in stable tumours, [2] increase of growth rate in growing tumours, and [3] inhibition of involution. In patients exhibiting tumour growth, average volume doubling times of about 2 years were found (5). Furthermore, many patients have a long history of various symptoms that could be related to the likelihood of using a mobile phone and the intensity of use as well as the side of the head it is used. Several studies found indications of reduced prevalence of use or of using the mobile phone on the opposite side of the head (which is also the case in the Japanese study reporting a significant association with contralateral use). Considering this evidence, what would be the result of a case-control study under the assumption mobile phone use has effects of the three types stated above? Obviously it must be negative if duration of mobile phone use is short, because a factor that is related to tumour growth can only reduce the latency until diagnosis by a fraction of the duration of exposure. Because average duration of use in the Japanese investigation was less than 4 years, it is impossible to find an effect even if mobile phone use would substantially increase growth rate of acoustic neuroma. Furthermore, because patients might reduce or even discontinue use of a mobile phone due to their symptoms (hearing impairments, tinnitus etc.) cumulative duration and intensity of use is not the most appropriate variable for analysis. Instead time between first use and occurrence of first symptoms should be taken into consideration. But still, observing that only 4 cases had used a mobile phone for 8 or more years, such an analysis would hardly have sufficient power to detect a promotional effect. For these reasons it would be appropriate to express some caveats as to the implications of the findings in this investigation. The combined evidence of 5 studies (6-10) that considered mobile phone use of at least five years is compatible with the assumption of a moderately increased risk. Except one study (8) all had odds-ratios above one and a combined estimate of about 1.5 that is statistically significant.

  1. Takebayashi T, Akiba S, Kikuchi Y, et al. Mobile phone use and acoustic neuroma risk in Japan. Occup Environ Med 2006; 63: 802-807 2. Anderson TD, Loevner LA, Bigelow DC, et al. Prevalence of unsuspected acoustic neuroma found by magnetic-resonance-imaging. Otol H N Surg 2000; 122:643-6. 3. Rosenberg SI. Natural history of acoustic neuromas. Laryngoscope 2000; 110:497-508. 4. Mohyuddin A, Vokurka EA, Evans DGR, et al. Is clinical growth index a reliable predictor of tumour growth in vestibular schwannomas? Clin Otolaringol 2003; 28:85-90. 5. Steinhart H, Triebswetter F, Wolf S, et al. Growth of sporadic vestibular schwannomas correlates with Ki-67 proliferation index. Laryngo- Rhino-Otol 2003; 82:318-21. 6. Inskip PD, Tarone RE, Hatch EE, et al. Cellular-telephone use and brain tumors. New Engl J Med 2001; 344:79-86. 7. Lönn S, Ahlbom A, Hall P, Feychting M. Mobile phone use and the risk of acoustic neuroma. Epidemiology 2004; 15: 653–659. 8. Christensen HC, Schüz J, Kosteljanetz M, et al. Cellular telephone use and risk of acoustic neuroma. Am J Epidemiol 2004; 159:277-283. 9. Schoemaker MJ, Swerdlow AJ, Ahlbom A, et al. Mobile phone use and risk of acoustic neuroma: results of the Interphone case–control study in five North European countries. Brit J Cancer 2005; 93:842-848. 10. Hardell L, Carlberg M, Hansson Mild K. Pooled analysis of two case- control studies on the use of cellular and cordless telephones and the risk of benign brain tumours diagnosed during 1997-2003. Int J Oncol 2006; 28:509-518.

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  Conflict of Interest:
  None declared.

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