A new study investigating the link between cell phone use and brain tumors has yielded inconclusive results. Over 10,000 people took part in the study: cell phone users; non cell phone users; cell phone users who survived brain cancer as well as brain cancer survivors who had never used cell phones. The results will be published this week in the International Journal of Epidemiology.

"If we combine all users and compare them with non-users, the Interphone Study found no increase in brain cancer among users. In fact, surprisingly, we found that when we combine users independently of the amount of use, they had lower brain cancer risks than non-users," says an epidemiologist at the University of Montreal Hospital Research Center. "However, the study also found heavy users of cell phones appeared to be at a higher risk of brain tumours than non-users."

Why the discrepancy? The researchers are unsure. Attention has focused on the methodology of the study and, in particular, on the representativeness of the study subjects who participated. With participation rates in the range of 50 percent to 60 percent of eligible subjects, it is possible that the participants did not provide an accurate portrait of cell phone usage among cancer cases and among healthy control subjects. Dr. Siemiatycki argues this problem arose because of constraints imposed on researchers by ethics committees intended to protect potential research subjects.

"Ethics reviews are now so rigid that scientists from Canada, the United States and Europe are losing the kind of access to medical databases and to study subjects that is needed to conduct studies such as this one. Ethics committees increasingly require that researchers work through treating physicians, professionals who are already overworked, to recruit their patients. This may work for clinical research exploring treatment of cancer, in which physicians often have a professional or personal interest, but it does not work for investigations into the causes of cancer. This flawed system can produce biased study results."

Despite the inconclusive results of the Interphone Study, consumers should not panic about possible risks related to cell phones, stresses Dr. Siemiatycki. "If there are risks, they are probably pretty small. Should anyone be concerned about potential dangers of cell phones, they can remedy the issue by using hands-free devices and avoid exposure to radio frequencies around their head."



Citation: The INTERPHONE Study Group, 'Brain tumour risk in relation to mobile telephone use: results of the INTERPHONE international case-control study', International Journal of Epidemiology, 2010, 1-20; doi: 10.1093/ije/dyq079