Some contraceptive pills, jabs and coils may put women at a higher risk of developing brain tumours, major research has found.
In a study of three million women, Danish scientists found pregnancy-preventing drugs named progestogens were linked to cases of meningioma.
Progestogens are synthetic versions of the female hormone, progesterone, and are found in contraceptives taken by millions of women in the UK. Studies have previously linked the drugs to tumours like meningiomas, which, research has shown, women have a greater likelihood of developing.
More than a quarter of brain tumours diagnosed in Britain are meningiomas, accounting for around 3,000 cases each year – making them the most common type.
Most meningiomas are benign, meaning they are non-cancerous, however they can press on the brain or spinal cord as they grow, triggering symptoms such as headaches, seizures and vision problems. They may require surgery or radiotherapy.
Cancer Research UK says the cause of meningiomas is ‘unclear’, but the new study has found that some contraceptives – particularly one popular injection – could raise the risk of developing the tumours by more than 350 per cent.
Experts said the findings should help inform important discussions between doctors and patients about the risks and benefits of various contraceptives.
The study, published in JAMA Network Open, analysed health records of three million women between the ages of 15 and 59, over a period of 25 years. The average age of the women was 48.
Some contraceptive pills, jabs and coils may put women at a greater risk of developing brain tumours, a major study has found
Researchers compared 1,473 women diagnosed with meningioma with 14,717 women who did not have the tumour.
The strongest link to meningioma in the study was seen among those taking the injection medroxyprogesterone. Those taking the jab were linked to 355 per cent higher odds of developing the tumour, compared to people who did not take it.
Medroxyprogesterone is commonly prescribed in Britain under the brand name Depo-Provera and is given to thousands of women.
Overall, the oldest women in the study faced the highest risk of developing meningioma.
For example, among women aged 55 to 59, there was one extra case of meningioma for every 5,372 women using the contraceptive injection for one year, compared with one extra case for nearly 449,000 women aged 15 to 19.
The study team also found that combined contraceptive pills – containing both oestrogen and a progestogen – could increase the odds of developing meningioma by up to 66 per cent.
These included cyproterone (61 per cent), desogestrel (66 per cent), drospirenone (58 per cent), gestodene (44 per cent), levonorgestrel (40 per cent), norethisterone (38 per cent) and norgestimate (4 per cent).
Levonorgestrel and norethisterone are among the progestogens that have been used in contraceptives for decades and are found in well-known brands like Microgynon, Rigevidon and Brevinor.
For progestogen-only pills, known as mini pills, desogestrel was linked with a 73 per cent increase in the odds of developing meningioma. Norethisterone, however, showed no clear risk increase.
Desogestrel is one of the most commonly prescribed mini pills in Britain and is sold under brand names including Cerazette and Cerelle.
Women using coils containing high-dose levonorgestrel also had a 58 per cent increase in the odds of developing meningioma, while no clear increase in risk was found for low-dose levonorgestrel.
The NHS says natural family planning can be up to 99 per cent effective when done correctly and around 75 per cent if not used according to instructions. By comparison, the Pill, implant, IUS and IUD are 99 per cent effective with perfect use, while condoms are 98 per cent
The authors, from the Danish Medicines Agency in Copenhagen, wrote: ‘These findings suggest that the risk of meningioma may extend beyond high-dose progestogens and medroxyprogesterone injections to include some contraceptive progestogens, including high-dose intrauterine devices with levonorgestrel.’
Importantly, the researchers found the risk generally disappeared within five years of stopping the contraceptive.
The team was unable to draw conclusions about several other progestogen-containing contraceptives because too few women had used them or too few cases of meningioma occurred.
These included etynodiol, lynestrenol, nomegestrol, dienogest, norelgestromin, drospirenone used as a progestogen-only pill, levonorgestrel used as a progestogen-only pill, and etonogestrel used in implants and vaginal rings.
The study also found no clear increase in risk for the combined pill norgestimate, the progestogen-only pill norethisterone, or the low-dose levonorgestrel coil.
Experts not involved in the research welcomed the study but stressed that the overall risk to women remained small.
Paul Pharoah, professor of cancer epidemiology at Cedars-Sinai Health Sciences University, said: ‘Importantly [the researchers] found that this risk only persisted while the women were using the hormonal contraceptive and declined once they stopped.
‘This is an observational study and determining that the observed associations are causal is difficult as it is hard to exclude all possible confounders. However, given all the available evidence it seems likely that the association is causal.’
Channa Jayasena, professor of reproductive endocrinology at Imperial College London, said: ‘All medications have risk, and contraceptive medications are no different. As the paper correctly states, the overall chance of these drugs giving you a meningioma is tiny.’
Gino Pecoraro, associate professor of obstetrics and gynaecology at the University of Queensland, added: ‘Prescribers should certainly be aware of the association between progestogen exposure and meningioma and also of non-progestogen-containing contraceptive options, including barrier methods and copper-containing IUDs should this association be of concern to the woman.
‘This is further evidence of the importance of appropriate contraceptive consultations addressing risks and benefits of various means of contraception, taking place between prescribers and women, prior to writing a script or making a recommendation.’
