New research published in JAMA Network Open has shed further light on the long-suspected link between progestogen-based hormonal contraception and the incidence of meningioma brain tumours. The large population-based study, which analysed routinely collected data from Denmark, confirmed an association, particularly noting a higher risk with injectable forms of contraception.
Professor Melanie Davies, Professor of Reproductive Medicine at UCL and Consultant Gynaecologist at University College London Hospitals, described the study as a “helpful addition to the literature.” She noted that it has been known for some time that meningiomas are more prevalent in women than men, suggesting a hormonal influence, and that most meningiomas possess progesterone receptors. While progestogens are widely used in hormonal contraception, and also in treatments for gynaecological conditions and some types of HRT, this specific study focused solely on contraceptive use.
The findings indicate a stronger association for medroxyprogesterone injections, showing a relative increase in risk of about four-fold. For several other progestogens used in different contraceptive formulations, the relative risk increase was approximately 1.5-fold. Importantly, the study observed that this increased risk subsided once women ceased using the hormonal contraceptive. Professor Paul Pharoah, Professor of Cancer Epidemiology at Cedars-Sinai Health Sciences University, commented that the study was “carefully carried out and analysed” and its findings were consistent with previous research.
Despite the relative increase in risk, experts are keen to stress that meningioma remains an exceptionally rare condition. Professor Davies highlighted that it affects only about one in ten thousand people. Professor Pharoah further explained that while a four-fold relative increase might sound significant, the absolute risk is small. He calculated that approximately five women per 1,000 will develop a meningioma in their lifetime, which increases to six per 1,000 for a woman using medroxyprogesterone from age 25 to 44, representing the highest-risk contraceptive studied. The increase in risk for other hormonal contraceptives is considered very small.
Professor Channa Jayasena, Professor of Reproductive Endocrinology at Imperial College London, underscored the vital role contraceptives play in society for women wanting to avoid pregnancy. All three experts emphasised that women should not be deterred from using progestogen-based contraception without first consulting their doctor. The benefits of effective hormonal treatments for contraception and debilitating conditions, they argue, must be carefully balanced against the very small absolute increase in the risk of developing a rare tumour.