Infections could play a key role in triggering certain types of adult brain cancer, scientists suggest.
Glioma tumours make up about half of all brain tumours
An international research team, led by Newcastle University experts analysed a database of brain tumour cases.
They found clusters at different times in different places, as seen with other conditions caused by infections.
The findings, in the European Journal of Cancer, may help development of better preventative measures for cancer and better treatments.
Brain cancer is not very common and, unlike many other cancers, does not usually spread to other parts of the body.
About 2,500 men and 1,800 women are diagnosed with brain cancer each year in the UK.
The British and Dutch team analysed data from the Eindhoven Cancer Registry between 1983 and 2001, of patients with brain tumours in the North Brabant province of the Netherlands.
They found clusters of cases of glioma tumours, which make up about half of all brain tumours, at different time intervals in different geographical locations
Many cases occurred at the same time in men and women over 15-years old in the East, but not in the West of the province.
Around 7% more cases of brain tumours were observed to occur in 'clusters' than would be expected by chance.
However, the research team said it was too early to say exactly which infections could be the cause, and say that more research is needed to pinpoint what they are.
This 'space-time clustering' of cases is a typical of diseases caused by infections, and the researchers say their findings add weight to the theory that outbreaks of viruses are a potential contributory cause of brain tumours.
Diseases caused by more constant environmental factors, such as pollution, produce clusters of cases in one place over a much longer time period.
The study is also in line with previous research which found similar clustering patterns in child brain cancers and leukaemia.
Dr Richard McNally, of Newcastle University's School of Clinical Medical Sciences (Child Health), said: "Very little is known about the cause of brain tumours and we think our research brings us closer to understanding more about this disease.
"We only found clustering of cases in the East of the province we investigated, and we think it could be something to do with the way infections spread in less densely populated areas."
However, the researchers stress that people cannot 'catch' cancer.
They say infections are only likely to trigger cancer in a very small number of individuals who are already genetically susceptible to the disease.
Dr McNally, added: "Future research should try to identify specific infections which could potentially be a trigger.
"If these are found, it could lead to future preventative measures."
Professor John Toy, Cancer Research UK's medical director, said: "Brain cancer is rare, accounting for less than 2% of all new adult cancers diagnosed in the UK each year.
"These findings suggest a possible link between infection and this type of the disease but by no means provide proof."
The study was funded by Cancer Research UK, the Dutch Cancer Society, and the Christie Hospital Research Endowment Fund.