Study ties some birth control to brain tumours, but risks ‘rare’: experts

Women using specific types of birth control may face a slightly elevated risk of developing meningioma, a type of brain tumor, according to a new study from Denmark. However, researchers and medical experts stress that the overall risk is "extremely rare" and typically diminishes within a few years of stopping the medication.

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Several progestogen-containing contraceptives were associated with an increased risk of meningioma. The risk estimates were highest for medroxyprogesterone injections.

The study, published in the Journal of the American Medical Association, analyzed data from approximately three million Danish women aged 15 to 59 between 2000 and 2024. It found an association between the use of contraceptive progestogens, present in oral pills, injections, and intrauterine devices (IUDs), and an increased risk of meningioma.

The findings indicate that injectable medroxyprogesterone was linked to the highest risk, making users four times more likely to develop the tumor compared to non-users. Other contraceptives, including combined oral contraceptives with specific hormones and certain IUDs, also showed a slightly increased risk. The risk was most pronounced in patients who had used these medications in the past year.

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An increased risk was also found for combined oral contraceptives with cyproterone, desogestrel, drospirenone, gestodene, and levonorgestrel; for desogestrel as progestogen-only contraceptive; and for high-dose IUD. Generally, [five] years after discontinuation, the increased risk was no longer present.

Dr. Derek Tsang, an oncologist at the Princess Margaret Cancer Centre, explained that progestogens can potentially stimulate the growth of existing meningiomas by binding to specific receptors. He noted that since women naturally produce progestogens, they are inherently more susceptible to meningiomas than men.

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I see many patients with meningiomas in my practice and we’ve always sort of known about this association with progesterone exposure and potential meningioma growth.

Despite the study's findings, experts urge against panic. They highlight that meningioma is a rare condition, affecting about one in ten thousand people. The potential benefits of effective hormonal contraception, they argue, should be weighed against this very small increase in risk.

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If the patient is exposed to progestogen and if it touches the meningioma, it binds to this receptor and that can be potentially what makes it grow.