A Danish study has revealed that hormonal contraceptives used by millions of women worldwide may be linked to a significantly increased risk of developing a common type of brain tumor known as a meningioma.
Researchers analyzed the health records of more than three million women, aged 15 to 59, over a quarter of a century and found that contraceptives containing the hormone progestogen, whether pills, injections, or intrauterine devices, were associated with a significantly higher likelihood of developing this tumor.
A meningioma is a non-cancerous tumor that usually grows in the membranes surrounding the brain and spinal cord. Although most meningiomas are benign, they can cause bothersome symptoms such as headaches, seizures, and vision problems as they grow and press on surrounding tissues, and in some cases may require surgery or radiation therapy.
The study showed that the strongest association with risk was with one commonly used contraceptive injection, which increased the likelihood of developing meningioma by 355% compared to non-users.
The risk was also found to be highest among older women, with researchers estimating that in the 55-59 age group, there was one additional case of meningioma for every 5,372 women using the injection for a year, compared to one additional case for every 449,000 users in the 15-19 age group.
The findings were not limited to injections but also included several combined oral contraceptive pills that combine estrogen and progestogens. The highest increased risk was associated with desogestrel, at 66%, followed by other drugs with varying percentages: cyproterone (61%), drospirenone (58%), gestodene (44%), levonorgestrel (40%), norethisterone (38%), and norgestimate (4%). It is worth noting that levonorgestrel and norethisterone are among the most commonly used progestogens in contraceptives and are found in well-known brand names such as Microgynon, Rigevidon, and Prevnor.
As for the mini-pills (containing only progestogen), desogestrel was associated with a 73% increased risk, while norethisterone-only pills showed no significant increase.
Regarding intrauterine devices (IUDs), the study found that high-dose levonorgestrel IUDs were associated with a 58% increased risk, while no increase was recorded with low-dose IUDs.
The researchers from the Danish Medicines Agency wrote in the journal JAMA Network Open that these findings suggest that the risk of meningioma may not be limited to high-dose treatments or Depo-Provera injections, but extends to some common progestogens in daily contraceptives.
Reassuringly, the study observed a general decline in this risk within five years of women stopping the use of those methods.
However, the researchers were unable to draw definitive conclusions about a number of other progestogen-containing contraceptives, either because of the small number of users or the rarity of meningioma cases recorded during the study period. These included etonodiol, linstriol, nomgestrol, dienogest, norelgestromin, drospirenone and levonorgestrel single pills, as well as etonogestrel implants and vaginal rings.
The study also did not find any clear increase in risk with combined norgestimate pills, norethisterone single pills, or low-dose levonorgestrel IUDs.
Experts not involved in the study confirmed that the overall risk of developing meningioma from hormonal contraceptives remains low and decreases after discontinuation, calling for a thorough discussion between the doctor and the patient about the risks and benefits, with the possibility of resorting to progestogen-free alternatives for those who are concerned.
