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, although there is also evidence that contraceptive use may reduce the risk in certain age groups, researchers said.
"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 Dr David Gaist of the Odense University Hospital and University of Southern Denmark.
They found 317 cases and compared each of these women with eight age-matched women who didn't have gliomas.
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"It is important to keep this apparent increase in risk in context," said Gaist.
"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," Gaist added.
The study was published in the British Journal of Clinical Pharmacology.