London, Jan 22 (IANS): A new study has found that taking a hormonal contraceptive for at least five years is associated with a possible increase in a young woman's risk of developing a rare tumour of the brain.

Hormonal contraceptives including oral contraceptives contain female sex hormones and are widely used by women all over the world.

While only a little is known about the causes of glioma and other brain tumours, there is some evidence that female sex hormones may increase the risk of some cancer types.

"This prompted us to evaluate whether using hormonal contraceptives might influence the risk of gliomas in women of the age range who use them," said research team leader David Gaist from Odense University Hospital and University of Southern Denmark.

The project focused on women aged 15-49 years and searched for those who had a first-time diagnosis of glioma between 2000 and 2009.

They found 317 cases and compared each of these women with eight age-matched women who did not have gliomas.

"It is important to keep this apparent increase in risk in context, " Gaist said.

"In a population of women in the reproductive age, including those who use hormonal contraceptives, you would anticipate seeing 5 in 100,000 people develop a glioma annually, according to the nationwide Danish Cancer Registry," he added.

"While we found a statistically significant association between hormonal contraceptive use and glioma risk, a risk-benefit evaluation would still favour the use of hormonal contraceptives in eligible users," Gaist emphasised.

It is important to carry on evaluating long-term contraceptive use in order to help women choose the best contraception for them.

"We hope that our findings will spark further research on the relationship between female hormonal agents and glioma risk," he concluded.

The findings were published in the British Journal of Clinical Pharmacology .