Mobile phone use and glioma risk: comparison of epidemiological study results with incidence trends in the United StatesBMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e1147 (Published 08 March 2012) Cite this as: BMJ 2012;344:e1147
- M P Little, senior scientist1,
- P Rajaraman, investigator1,
- R E Curtis, research statistician1,
- S S Devesa, contractor2,
- P D Inskip, senior investigator1,
- D P Check, programmer2,
- M S Linet, senior investigator1
- 1Radiation Epidemiology Branch, National Cancer Institute, Rockville, MD 20852-7238, USA
- 2Biostatistics Branch, National Cancer Institute
- Correspondence to: M P Little
- Accepted 3 January 2012
Objective In view of mobile phone exposure being classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC), we determined the compatibility of two recent reports of glioma risk (forming the basis of the IARC’s classification) with observed incidence trends in the United States.
Design Comparison of observed rates with projected rates of glioma incidence for 1997-2008. We estimated projected rates by combining relative risks reported in the 2010 Interphone study and a 2011 Swedish study by Hardell and colleagues with rates adjusted for age, registry, and sex; data for mobile phone use; and various latency periods.
Setting US population based data for glioma incidence in 1992-2008, from 12 registries in the Surveillance, Epidemiology, and End Results (SEER) programme (Atlanta, Detroit, Los Angeles, San Francisco, San Jose-Monterey, Seattle, rural Georgia, Connecticut, Hawaii, Iowa, New Mexico, and Utah).
Participants Data for 24 813 non-Hispanic white people diagnosed with glioma at age 18 years or older.
Results Age specific incidence rates of glioma remained generally constant in 1992-2008 (−0.02% change per year, 95% confidence interval −0.28% to 0.25%), a period coinciding with a substantial increase in mobile phone use from close to 0% to almost 100% of the US population. If phone use was associated with glioma risk, we expected glioma incidence rates to be higher than those observed, even with a latency period of 10 years and low relative risks (1.5). Based on relative risks of glioma by tumour latency and cumulative hours of phone use in the Swedish study, predicted rates should have been at least 40% higher than observed rates in 2008. However, predicted glioma rates based on the small proportion of highly exposed people in the Interphone study could be consistent with the observed data. Results remained valid if we used either non-regular users or low users of mobile phones as the baseline category, and if we constrained relative risks to be more than 1.
Conclusions Raised risks of glioma with mobile phone use, as reported by one (Swedish) study forming the basis of the IARC’s re-evaluation of mobile phone exposure, are not consistent with observed incidence trends in US population data, although the US data could be consistent with the modest excess risks in the Interphone study.
Funding: This work was supported by the Intramural Research Program of the National Institutes of Health, and the National Cancer Institute, Division of Cancer Epidemiology and Genetics.
Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: funding support from the Intramural Research Program of the National Institutes of Health, and the National Cancer Institute, Division of Cancer Epidemiology and Genetics; no financial relationships with any organisations that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: Data from the SEER registry have no personal identifying information and therefore ethical approval not required.
Contributors: MPL did the statistical analysis and is the data guarantor. All the authors contributed to the drafting of the manuscript, had full access to all the data (including statistical reports and tables) in the study, and take responsibility for the integrity of the data and the accuracy of the data analysis.
Data sharing: The SEER data described in this study and web appendix are freely available on application to SEER (http://seer.cancer.gov/data/). The statistical codes used are available from the corresponding author.
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