Bias "mars mobile phone cancer research"

 

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By Reuters

Posted on 14 Oct 2009 at 08:14

Studies on whether mobile phones cause cancer vary widely in quality and exhibit bias in those showing the least risk, according to researchers.

So far it's difficult to demonstrate any link, although the best studies do suggest some association between mobile phone use and cancer, according to the team led by Dr Seung-Kwon Myung of South Korea's National Cancer Center found.

Funding for the lower-quality studies included two industry groups, the Mobile Manufacturers Forum and the Global System for Mobile Communication Association

Myung and colleagues at Ewha Womans University and Seoul National University Hospital in Seoul and the University of California, examined 23 published studies of more than 37,000 people in what is called a meta-analysis.

They found results often depended on who conducted the study and how well they controlled for bias and other errors. "We found a large discrepancy in the association between mobile phone use and tumour risk by research group, which is confounded with the methodological quality of the research," they write in the Journal of Clinical Oncology.

Mild increased risk

Myung's team claims eight studies that employed "high quality" methods to blind participants against bias found a mild increased risk of tumours among people who used mobile phones compared with those who never or rarely did. An increased risk of benign, not malignant, tumours was also found among people who used the phones for a decade or longer.

The "high quality" studies were funded by the Swedish Work Environment Fund, the Orebro Cancer Fund and the Orebro University Hospital Cancer Fund, Myung's team says.

By contrast, studies that used "low quality" methods to weed out bias found mobile users were at lower risk for tumours than people who rarely used the devices. Myung's team suggested those results could be marred by random errors and bias because of the quality of the methods.

Funding for some of the lower-quality studies included two industry groups, the Mobile Manufacturers Forum and the Global System for Mobile Communication Association, the researchers claim.

Overall, the studies examined were not broad enough to shed light on whether mobile phone use could cause cancer. Myung's team says larger studies of a type called cohort studies are needed to answer that question.

Such studies follow a group of people who share a characteristic, in this case mobile phone use, and compare them with other groups over time.

The only cohort study published to date showed no association between mobile phone use and tumours. But the study, conducted in Denmark, relied on telephone subscriptions and did not evaluate actual exposure to mobile phones.

Upwardly mobile

The use of mobile phones has exploded in the past decade to an estimated 4.6 billion subscribers worldwide, according to the UN International Telecommunication Union.

The latest study, supported in part by the US Centers for Disease Control and Prevention, examined cases involving brain tumours and others including tumours of the facial nerves, salivary glands and testicles as well as non-Hodgkin's lymphomas. It found no significant association between the risk of tumours and overall use of mobile phones, including cellular and cordless phones.