[ RadSafe ] Glioma and Cell Phones -- Again No Link

[Susan Gawarecki]

Glioma and Cell Phones -- Again No Link
By Michael Smith , MedPage Today Staff Writer
Source News Article: BBC News, Forbes

LEEDS, England, Jan. 19 - Call your friends (but watch your minutes). 
The largest study yet has found no link between long-term cell-phone use 
and the risk of brain cancer.

British researchers determined no association between the risk of glioma 
and time since first cell-phone use, lifetime years of use, and 
cumulative number of calls and hours of use, according to Sarah 
Hepworth, Ph.D., a medical statistician at the Leeds Institute of 
Genetics, Health, and Therapeutics here.

The study is in accord with most studies that have examined the highly 
publicized notion that radio frequencies emitted by cell phones can 
cause cancer, concluded Dr. Hepworth and colleagues at the Universities 
of Leeds, Manchester and Nottingham and the Institute of Cancer Research 
in London.

In general, there is “a lack of convincing and consistent evidence” that 
exposure to radio waves causes cancer and “our findings are consistent 
with this,” the researchers said today in the online issue of the BMJ, 
formerly the British Medical Journal.

Over a four-year period, Dr. Hepworth and colleagues obtained data on 
966 patients diagnosed with gliomas in five regions of the United 
Kingdom that included nearly half of the population. Also, 1,716 age- 
and sex-matched controls were selected from lists of those enrolled with 
a general practitioner.

Interviews with cases and controls elicited information about cell-phone 
use, although the study was presented to participants as part of a broad 
investigation of the risk factors for glioma without emphasizing cell 
phones.

Patients who rarely or never used a cell phone were used as a reference 
group. The study found:

* In terms of frequency of use, there was little difference between 
cases and controls; slightly more than half of each group (52.6% versus 
52.3%) used a cell phone regularly.
* There was no association between risk of glioma and years since first 
use, lifetime years of use, cumulative hours of use, and cumulative 
number of calls. In all cases, the odds ratios were close to 1.00 and 
the 95% confidence intervals crossed unity. The association between cell 
phone use and glioma was adjusted for age, gender, region where the 
patient came from, and deprivation score (measure of socioeconomic status).
* Tumor grade and frequency of use also did not yield a significant 
association.

In fact, the researchers said, the only significant association they 
could find was that there were more tumors of the side of the head where 
the phone was usually used, and fewer on the other side.

The odds ratio for the ipsilateral side was 1.24, with a 95% confidence 
interval from 1.02 to 1.52, while the odds ratio for the contralateral 
side was 0.75, with the 95% confidence interval ranging from 0.61 to 0.93.

The finding, though, probably can be explained by recall bias, the 
researchers argued. “Patients with glioma, who were aware of the 
location of their tumor, may have considered that mobile phone use was a 
cause of its development, resulting in systematically over-reporting of 
phone use on the side of the head where their cancer occurred,” they noted.

Last year, case-control studies in Sweden and Denmark led to similar 
conclusions, although neither study was as large as the investigation 
conducted by Dr. Hepworth and colleagues.

(a 
href="http://www.medpagetoday.com/HematologyOncology/BrainCancer/tb1/861" 
target="blank">; Lonn S et al. Long-term mobile phone use and brain 
tumor risk. Am J Epidemiol. 2005 Mar 15;161(6):526-35.)

Primary source: British Medical Journal
Source reference:
Hepworth SJ et al. Mobile phone use and risk of glioma in adults: 
case-control study. BMJ 2006; doi 10.1136/bmj.38720.687975.55.