12 August 2010

Finding the Link Between Cellphone Use and Tumors

This article touches on a long-term study examining the parallels of cell phone use and whether such behavior causes brain tumors. The press reports reflecting the study were very ambiguous; the study either expressed in vague conclusion that there was no risk, that there was some risk, or that the overall findings in the study were inconclusive.

“This perhaps speaks to the oracular nature of the findings,” commented USC professor of preventive medicine, Jonathan Samet regarding the scope of the study.

This coincides with past research regarding the cellphone and tumor link, which has also failed to fully determine whether using a cellphone is considered hazardous. “It’s unfortunate that we’re so far into the adoption of this technology and we know so little about the long-term effects — or about the short-term effects for that matter,” said Joel Moskowitz, director of USC's Center for Family and Community Health in Berkeley.

The new, long-term study was under a "case-control" format, however the term 'control' has induced some confusion with respect to the study's validity. In a study of a major drug company’s new pharmaceutical, individuals who were administered the drug are compared with a group of people who don’t — a control group. What makes the approach of the cellphone study questionable is brain cancer is so rare that the study would have to recruit a huge number of participants in order to identify minor differences in cancer rates (approximately six diagnoses for every 100,000 Americans per year). That being the underlying task for researchers, or cellphone usage would have to impose an enormous impact on cancer rates, comparable to cigarette smoking’s influence on lung cancer. “You can do a really lousy job [with a study] and still find out that smoking causes lung cancer,” said Dan Wartenberg, professor of occupational medicine at Robert Wood Johnson Medical School.

So when conducting case-control studies, the cases and controls are different based on outcome, rather than input (input being the use of cellphones). Individuals with and without brain tumors were chosen to match on other contributing factors - and then their cellphone use was analyzed and compared.

The primary issue with this approach is that several individuals without brain tumors who did not use cellphones all that much seemed unmotivated and less willing to participate. This being due to an overall lack of financial incentives to participate, in addition to several participants being told that the study focuses on cellphone use - a behavior that had little to do with the group. With respect to these factors, the control group may not have adequately matched the case group.

“There are several ways to overcome those biases with case-control studies,” said Seung-Kwon Myung, who has prior experience studying the potential link between cellphone use and brain tumors. “First, if possible, reducing the items of the questionnaire and the time for the interview could be effective in order to avoid non-response biases. Second, provide a participant with enough reward or incentive. Last, increase the sample size.”

Ensuring the overall control of a study with such social implications is crucial, and with so many uncontrollables and variables involved, having a sufficient sample size is a sound approach to improve the quality of the results, as summarized by one cancer care Wayne county researcher and neurosurgeon.

Among the other issues when comparing individuals with cancer against those who are cancer-free include: Those in the study who developed a tumor may have encountered cancer symptoms far before they were actually diagnosed. Specific symptoms such as epilepsy could limit cancer sufferers’ cellphone use and minimize their tally of hours on the phone. In addition, there is always the unforeseeable risk that participants in each group might not have been exposed to equal levels of other potential cancer risks, such as radiation exposure from medical evaluations or being in close proximity to cell towers.

As a result of the case-control study, the findings expressed that using cellphones actually protect against cancer, a discovery that the average brain tumor specialist considers implausible. There was one unique association between extensive cellphone use and the forming of a tumor called glioma, which utilizes gamma knife surgery for treatment. However, with respect to the vast number of tests performed in the study, there is the possibility that one of the cases was statistically significant by chance.

In order to overcome the matching control problems, researchers also tried another form of analysis which omitted non-cellphone users from the study. The alternative approach showed an elevated risk in use, however some researchers considered it inappropriate to perform a different analysis after the initial study was taken. A St. Louis neurosurgeon interested in the study reinforced that undergoing a completely new approach that results in entirely new findings can sometimes prompt more debate and controversy, straying from the true scope of the study.

“A fundamental principle of research is to prospectively and explicitly specify the analyses in advance,” said Donald Berry of MD Anderson Cancer Center. “…the level of compellingness required to enable a positive conclusion increases with the number of analyses. I don’t see anything like that level here.”

The disagreements among researchers regarding the data delayed publication of the study's findings. “There were genuine differences in opinion about the interpretation of the results, and these differences needed to be adequately explored in the manuscript,” said Christopher Wild, director of the World Health Organization’s International Agency for Research on Cancer in Lyon, which coordinated the study.

Furthermore, as more validity is established through different interpretations of the results, the need to dive into the data as well as the structure of the study is imperative; as summarized by a neurology specialist Dearborn.

“The main problem here is, it’s such a long time until it has been published,” voiced Martin Röösli, Swiss Tropical and Public Housing Institute epidemiologist. Martin is currently conducting his own unique case-control study targeting cellphone use and tumors in children, a demographic researchers are particularly concerned about due to the indications that early cellphone use may be even more risky. One critical issue with the study's delay is that cellphone use has greatly evolved. According to the wireless trade group CTIA, the average American cellphone was used for 133 hours last year. That statistic is substantially higher than the amount of use without headsets by cellphone using participants in the study over their entire lifetimes. Yet people are implementing headsets to talk on their cellphones, in addition to using their phones more for text messaging and accessing the Web. Not to mention, today's cellphone technology gives off less radiation than in the past.

“You can find so many weaknesses in epidemiological research,” Röösli commented. “But you still you need to do it because otherwise you don’t have anything at all.”

“There’s an obligation of government and society to really provide information about risks so that people can make rational judgments and also to do what they can to reduce risks,” said David O. Carpenter, the director of the University at Albany’s Institute for Health and the Environment.

“Was it worth it?” said Bruce Armstrong, co-author of the study and professor of public health and population medicine at Australia's Sydney School of Public Health. “In hindsight, the knowledge yield is low relative to the cost. In prospect it was a necessary expense and society will almost certainly judge that further expense is necessary.”

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