According to Cancer Research UK, doctors diagnose about 9,400 people a year with gliomas and other CNS or intracranial tumours. Now research suggests that long-term users of hormonal contraceptives are nearly twice as likely to develop gliomas as non-users. Using registries in Denmark, researchers identified 317 women aged 15-49 years with a first-time diagnosis of glioma. Women who had ever used hormonal contraceptives were 50 per cent more likely to have a glioma than controls. Women who used hormonal contraception for at least five years were 90 per cent more likely to develop a glioma. The link was stronger for use within the last two to five years (odds ratio [OR] 1.7) than for use more than five years previously (OR 1.2).

The researchers disregarded contraceptive use in the last two years to avoid potential confounders. “It is important to keep this apparent increase in risk in context,” says David Gaist of Odense University Hospital and the University of Southern Denmark. “In a population of women in the reproductive age, including those who use hormonal contraceptives, you would anticipate seeing five in 100,000 people develop a glioma annually, according to the nationwide Danish Cancer Registry. “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,” he commented. (British Journal of Clinical Pharmacology DOI:10.1111/ bcp.12535)

Increased risk of gliomas found