October 14, 2009

Mobile Phones And Cancer

Studies into the potential link between the use of cell phones and cancer differ broadly in terms of quality, and may include some bias among those showing minimal risk, said South Korean scientists on Tuesday.

Although no conclusive proof has been found that mobile phone use causes cancer, the best studies do suggest some association, according to researchers led by Dr. Seung-Kwon Myung of South Korea's National Cancer Center.

Myung and his colleagues conducted a meta-analysis of 23 published studies of more than 37,000 people, and found the results frequently depended upon who conducted study and how well they controlled for bias and other errors.

"We found a large discrepancy in the association between mobile phone use and tumor risk by research group, which is confounded with the methodological quality of the research," wrote the researchers in the Journal of Clinical Oncology.

The use of mobile and cordless phones has surged over the past decade, with some 4.6 billion people worldwide now using the devices, according to the United Nations International Telecommunication Union.

But studies have failed to establish any clear link between use of the phones and several types of cancer.

The latest research examined cases involving brain tumors, non-Hodgkin's lymphomas and other types of cancer including tumors of the facial nerves, salivary glands and testicles.  It found no significant association between the overall use of mobile phones and the risk of tumors.

However, eight studies that used "high-quality" techniques to blind participants against bias found a modest increase in tumor risk among people who used mobile phones compared with those who never or rarely did.

These "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 said.

An increased risk of benign, non-malignant tumors was also found among those who used the devices for ten years or longer.

By contrast, studies that employed "low-quality" methods to eliminate bias found mobile phone users were at lower risk of tumors than those who rarely used the devices.

Myung's team suggested that the results could be distorted by random errors and bias due to the quality of the methods used.

Some of the lower-quality studies were funded by the industry groups Mobile Manufacturers Forum and the Global System for Mobile Communication Association.

In general, the studies Myung and his team examined were not extensive enough to indicate whether mobile phone use could cause tumors.

Larger, cohort studies are needed to address that question, the researchers said.  Such studies follow participants who share a certain characteristic, in this case mobile phone use, and compare them with other groups over time.

The only published cohort study published to date showed no association between mobile phone use and tumors. However, the Danish study relied on telephone subscriptions and did not examine subscribers' actual mobile phone exposure.

Myung's study, which was supported in part by the U.S. Centers for Disease Control and Prevention, was published in the Journal of Clinical Oncology.


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