New Study Debunks Link Between Cell Phones and Gliomas

The hypothetical connection between cellular telephones and gliomas may turn out to be a wrong number. A growing body of research appears to refute, with mounting certainty, the claim that the ubiquitous cell phone can produce biologic changes in brain cells leading to cancer. The latest blow to the hypothesis is a rigorous population-based incident case-control study of gliomas and meningiomas among cell phone users appearing in the April edition of the journal Neurology.

The study in Denmark is part of a larger, forthcoming European Interphone Study conducted under the aegis of the International Agency for Research on Cancer (IARC).

The results are preliminary while we wait for the collaborative [Interphone] study, but the important take home message is that there was no increased risk of tumors for cell phone users, lead researcher H. Collatz Christensen, MD, told Neurology Today. She is with the Institute of Cancer Epidemiology at The Danish Cancer Society.

METHODOLOGY

Dr. Christensen and colleagues ascertained all incident cases of glioma and meningioma diagnosed in Denmark between September 1, 2000 and August 31, 2002. They enrolled 252 people with glioma and 175 persons with meningioma aged 20 to 69. The authors also enrolled 822 randomly sampled population-based controls matched for age and sex.

In face-to-face interviews respondents were asked if they had ever used a cellular telephone. If so, they were asked if they were regular users - defined as using the phone at least once a week for six months or more - and how many different cell phones they had used regularly.

For each cellular telephone used regularly, start and stop dates of use were recorded. If the respondent was still using the cellular telephone on the day of the interview, stop date was set at the date of diagnosis (for cases) or the reference date (for controls).

Participants in the study were also asked about the numbers of calls made and received and about the duration of calls on each cellular telephone used by the respondent, as well as about changes in the pattern of use over more than six months. This information was validated using detailed information about the frequency and duration of use of the most recent reported cellular telephone from the two largest cellular telephone network operators in Denmark. Information on tumor size and location was also obtained from cases.

NO INCREASED RISK FOUND

Results showed no increased risk for either glioma or meningioma in relation to use of a cellular telephone, frequency of use, time since first use, or various expressions of cumulative use.

In fact, the researchers actually found a decreased odds ratio for high-grade glioma among regular users of cell phones compared to non-users - a finding that Dr. Christensen said is likely to be the result of a methodological artifact.

EXPERTS COMMENT

Neurologist Lisa DeAngelis, MD, who reviewed the report for Neurology Today, called it a nicely done study that confirms findings from previous research. And though Dr. Christensen was more circumspect in interpreting the findings, Dr. DeAngelis said she believes the verdict is in on brain cancer and cell phone use.

This study validates the finding from other research, she said. The evidence is now very solid that cell phones do not cause brain cancer.

Dr. DeAngelis, Chairman of Neurology at the Memorial Sloan Kettering Cancer Center, New York, and a member of the editorial board of Neurology Today, said the strength of the data, and the methodological rigor of the study make the findings difficult to dismiss.

The Danish cancer registry is very well established, so they probably got every case of glioma or meningioma in the country, she said.

And she said the effort to look at the extent of cell phone use and the duration of calls in relationship to incidence of glioma and meningioma is also an important contribution.

Figure. Dr. Lisa DeA...

CONFIRMING EARLIER STUDIES

At least three other studies of varying sample sizes have found similar results. A 2002 study appearing in Neurology examined cell phone use among 90 patients with acoustic neuromas and 85 controls. That study found no association between acoustic neurinomas and cell phone use, and tumors in patients were located more frequently on the contralateral than on the ipsilateral side of the head (Neurology 2002;58:1304-1306).

Other studies reporting similar findings appeared in the New England Journal of Medicine (2001;344:79-86) and the Journal of the National Cancer Institute (2001;93:203-207).

According to the US Food and Drug Administration, basic research on the subject of radiofrequency energy and brain cancer has been conflicting.

Animal experiments investigating the effects of radiofrequency energy (RF) exposures characteristic of wireless phones have yielded conflicting results that often cannot be repeated in other laboratories, according to the FDA's Web site (www.fda.gov/cellphones/qa.html).

A few animal studies, however, have suggested that low levels of RF could accelerate the development of cancer in laboratory animals. However, many of the studies that showed increased tumor development used animals that had been genetically engineered or treated with cancer-causing chemicals so as to be pre-disposed to develop cancer in the absence of RF exposure.

MORE DATA TO COME

In the European Interphone study, it is expected that the studies will include about 6,000 cases of gliomas and meningiomas (both benign and malignant), 1,000 cases of acoustic neurinoma, 600 cases of parotid gland tumors and their respective controls.

Participating countries are Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden and the UK. In order to maximize the power of finding a risk if it exists, the studies are mainly focused on tumors in relatively young people (30-59 - who had the highest prevalence of mobile phone use 5 to 10 years ago) and on regions within the participating countries with the longest and highest use of mobile phones, according to the Web site of the International Agency for Research on Cancer (www.iarc.fr/ENG/Units/RCAd.html).

ARTICLE IN BRIEF

✓ A new population-based study of gliomas and meningiomas among cell phone users concludes that cell phones do not produce biologic changes in brain cells leading to cancer.