The use of oral contraceptives is known to increase the risk of certain cancers, but there have been few data on whether this applies to brain tumours.
But a study
has now used Danish registry data to identify all 317 cases of glioma, a type of brain tumour, occurring among women aged 15–49 years between 2000 and 2009, and matched them to 2,126 population controls. It found that that women who had used oral contraceptives had an increased risk of developing glioma compared with the general population (odds ratio 1.5, 95% confidence interval 1.2–2.0).
The risk of glioma was even higher in women who had used oral contraceptives for 5 years or more, and in women who had taken progestogen-only pills, with odds ratios of 1.9 and 2.4, respectively.