Friday, July 29, 2011

More Confusing Data Regarding Mobile Phone Use and Brain Tumors

On May 31, 2011, the World Health Organization (WHO) through the International Agency for Research on Cancer (IARC) classified mobile phone use as Group 2B or "possibly carcinogenic." A panel of 31 experts reached this conclusion after reviewing existing data--no new research was performed. Unfortunately, the classification as "possibly carcinogenic" by the WHO is essentially meaningless and provides the public with no useful information.

The most recent scientific article to address this issue, "Mobile Phone Use and Brain Tumors in Children and Adolescents: A Multicenter Case–Control Study," was published in the Journal of the National Cancer Institute on July 27, 2011. This was a multi-center case-controlled study conducted in Denmark, Sweden, Norway and Switzerland and included all patients aged 7-19 years diagnosed with a brain tumor. 352 brain tumor patients and 646 controls were interviewed regarding cell phone usage.

The conclusion that has received widespread press is that "Our primary analysis does not point to a statistically significantly increased risk for brain tumors in children that is associated with the use of mobile phones." In other words, cell phone use does not cause brain tumors in children or adolescents.

But is that the conclusion that should really be reached from this study? Short answer: NO.

First, the methodology is the repeatedly used and notoriously flawed case-control interview. This method has a variety of sources of error and it is unclear why it continues to be used and, importantly, funded.

Second, at least some funding is provided by major telecommunication companies: TellaSonera, Erickson AB and Telenor.

Third, when actual usage and subscription data are analyzed (as opposed to subjective interview data), the authors found "a statistically significantly increased risk among users with the longest period since first subscription." In other words, the risk of developing a brain tumor increased with longer cell phone use. Oddly, this conclusion did not make the headlines.

And lastly, the question asked in this study is close to but not quite what most of us want answered: Does the use of cell phones in childhood and adolescence increase the risk of developing a brain tumor in adulthood?

So, what is the take home message? The data on cell phone use and risk of brain tumor is conflicting. At this point, the published studies have limitations ranging from methodology errors, to funding conflicts of interest.

What should you do? Use the speaker phone feature. Use text messaging (except when driving). And limit mobile phone usage in children and adolescents.

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