Increased Cell Phone Usage Shows No Change in Brain Tumor Incidence

No substantial change in brain tumor incidence was detected among adults in Scandinavia in the years after cell phone usage increased sharply, according to a new study.

Researchers at the Institute of Cancer Epidemiology (Copenhagen, Denmark), the University of Tampere (Finland), the Karolinska Institutet (Stockholm, Sweden; ki.si), and the Norwegian Radiation Protection Authority (Norway) investigated time trends in the incidence of glioma and meningioma in Denmark, Finland, Norway, and Sweden from 1974 to 2003, using data from national cancer registries. The researchers then used join-point regression models to analyze the annual incidence rates of glioma and meningioma. During this period, 59,984 men and women aged 20-79 years were diagnosed with brain tumors, among a population of 16 million adults.

The researchers found that from 1974 to 2003 the incidence rate of glioma increased by 0.5% per year among men and by 0.2% per year among women, and that of meningioma increased by 0.8% per year among men, and after the early 1990s by 3.8% per year among women. These data indicated that the incidence rates over this 30 year-period were stable, decreased, or continued a gradual increase that started before the introduction of cell phones.

The researchers then examined the incidence trends in brain tumors only from 1998 to 2003, and found no difference in incidence rates. They explain that this finding may be due to one of several reasons: that the induction period relating cell phone use to brain tumors exceeds 5-10 years; that the increased risk in this population is too small to be observed; that the increased risk is restricted to subgroups of brain tumors or cell phone users; or that there is no increased risk. The authors did not assess cell phone usage at the individual level during this period, concentrating only on brain tumor incidence. The study was published early online on December 3, 2009, in the Journal of the National Cancer Institute.

"We did not detect any clear change in the long-term time trends in the incidence of brain tumors from 1998 to 2003 in any subgroup,” said lead author Isabelle Deltour, Ph.D., of the Institute of Cancer Epidemiology. "Because of the high prevalence of mobile phone exposure in this population and worldwide, longer follow-up of time trends in brain tumor incidence rates are warranted.”

Although cell phone use has been proposed as a risk factor for brain tumors, a biological mechanism to explain this association is not known.

Related Links:
Institute of Cancer Epidemiology
University of Tampere
Karolinska Institutet
Norwegian Radiation Protection Authority