The study, published in the Journal of the National Cancer Institute, identified 60,000 people from Denmark, Finland, Norway and Sweden who were diagnosed with glioma or meningioma brain cancer between 1974 and 2003. This was an era in which cellphone use increased dramatically, but the study showed that brain cancer rates over this period were stable, decreased or continued a gradual increase that started before the introduction of cellphones. The study did not examine individual patterns of cellphone use.
While the issue will continue to be controversial, the study is important because it mirrors the international Interphone case-control studies which have shown no overall increase in glioma or meningioma rates. The Interphone studies, however, "leave open the possibility of a small to moderate increased risk for glioma among the heaviest users of mobile phones," wrote the authors of today's paper from the Institute of Cancer Epidemiology, Danish Cancer Society. Swedish studies, they noted, have found increased risks for glioma in cellphone users.
It's possible that cellphone use must exceed five to 10 years before the growth of an associated brain tumor is observed, they said. Or it could be the risk is too small to be observed, is nonexistent or that the risk is linked to only a subgroup of brain cancers.
But, the authors wrote: "Because of the high prevalence of mobile phone exposure in this population and worldwide, longer follow-up time trends in brain tumor incidence rates are warranted."
- Shari Roan
Photo credit: Kejr Sasahara / Associated Press