The heaviest users of cell phones may be at higher than average risk of being diagnosed with a brain tumor, according to a recent French study.
But for most people, itís still not clear if thereís added risk, the authors say. Plus, the devices and the way people use them keeps evolving so that more research is needed going forward, they add.
This isnít the first study to point to a tumor risk with heavy cell phone use, said Dr. L. Dade Lunsford, a distinguished professor of neurosurgery specializing in brain tumor management at the University of Pittsburgh.
But these kinds of studies rely on people to recall how much they have used cell phones in the past with no indication of their actual use, said Lunsford, who was not involved in the French research.
The new results found no difference between regular cell users and non-users, which suggests that if there is a link, it is only applicable for people who claim to use their cell phone the most, he noted by email.
Cell phones emit radiofrequency electromagnetic fields in the microwave spectrum, which may be cancer causing, although thatís not yet proven, said Dr. Seung-Kwon Myung of South Korea's National Cancer Center.
Myung led a large analysis of all the previous studies of cell phone use and brain tumors.
In 2011, the World Health Organizationís International Agency on Cancer classified this radiation as possibly carcinogenic, based on existing studies.
The French team, led by Dr. Gaelle Coureau of the Universite Bordeaux Segalen, used a cancer registry to identify adults with meningiomas or gliomas, the two most common types of adult brain tumors.
Brain tumors are generally rare relative to other types of cancer. Less than eight in 100,000 people in the U.S. each year are diagnosed with meningiomas, and 85 percent of those tumors are benign, according to Johns Hopkins Medicine and the Cleveland Clinic.
Malignant brain tumors represent only two percent of all cancers.
The new analysis included 253 cases of glioma and 194 cases of meningioma in four French regions, and twice as many people from the same areas of France who had never had a brain tumor, for comparison.
Researchers interviewed the participants about their past cell phone use, with questions about the model of phone they had used, how long they had used it, the average number and length of calls made and received each month and whether the phones were used for work.