Using a cellphone does not seem to increase the risk of developing the most common type of brain tumour, a large British study suggests.

The study, in the Jan. 21 issue of the British Medical Journal, found no increased risk of "gliomas" with regular cellphone phone use.

There was also "no association with time since first use, lifetime years of use, cumulative hours of use or number of calls," it said.

The use of cell phones has risen rapidly worldwide over the last 20 years.
The use of cell phones has risen rapidly worldwide over the last 20 years.

Gliomas are the most deadly type of primary brain tumours, those that start in the brain rather than spreading from elsewhere in the body.

In the four-year survey, epidemiology Prof. Patricia McKinney of the University of Leeds and her colleagues compared 966 people with gliomas to 1,1716 healthy volunteers.

The survey is larger than previous published studies. Most conducted in the United States and Europe showed similar results.

Last year, a Swedish study suggested cellphones may pose a higher health risk in rural areas, where signals are more intense, but the British results didn't show the same pattern.

They also found no evidence of a difference in health risks from older analogue phones, which emit higher power signals compared to newer, digital models.

Recall problems

People with gliomas were more likely to report tumours on the side of the head they used most to listen to cellphones, McKinney's team found.

Patients may have overreported what side of the head they used because they thought cellphones may have caused the tumours, the researchers said.

Participants were asked how much they used their cellphones over the past 10 years, how often they used hands-free kits and what types of phones, and they were shown photographs of models to jog their memories.

Nevertheless, studies that rely on interviews with patients rather than medical records can be less reliable, and longer term research is needed on the development of gliomas. Few participants in the British study had used cellphones for more than 10 years, the researchers noted.

More than 4,000 new cases of brain tumours in Britain and about 20,000 in the United States are diagnosed each year.

The research was sponsored in part by cellphone manufacturers and network operators and the U.K. Department of Health.