London, Sep 17 (IANS): Being overweight or obese may increase risk of a type of brain tumor called meningioma, new research has found.

"This is an important finding since there are few known risk factors for meningioma and the ones we do know about are not things a person can change," said study author Gundula Behrens from University of Regensburg in Germany.

Meningiomas occur at a rate of about five to eight cases per 100,000 people per year.

The five-year survival rate for meningioma is 63 percent.

"Given the high prevalence of obesity and the unfavourable prognosis for this type of tumor, these findings may be relevant for strategies aimed at reducing the risk of meningioma," Behrens noted.

The researchers looked at all of the available research on body mass index (BMI), physical activity and the brain tumours meningioma and glioma, which are the most common primary brain tumors in adults.

A total of 12 studies on body mass index and six on physical activity were analysed, involving 2,982 meningioma cases and 3,057 glioma cases.

The analysis found that compared to people with a normal weight, overweight people were 21 percent more likely to develop a meningioma and obese people were 54 percent more likely to develop one.

Overweight was defined as having a BMI of 25 to 29.9; obese was considered a BMI of 30 or higher.

No relationship was found between excess weight and glioma, which occurs at about the same rate as meningioma but has a worse prognosis.

Those with the highest amount of physical activity were 27 percent less likely to have a meningioma than those with the lowest amount of activity.

The study appeared online in the journal Neurology.