A new study published in the British Medical Journal has suggested that some contraceptive injections containing progestogens could increase the risk of developing a rare type of brain tumour.
The contraceptive injection (medroxyprogesterone acetate or Depo Provera) is a large dose of progesterone given every 3 months. This injection stops women from ovulating, and is prescribed by the HSE.
The study, led by the French National Agency for Medicines and Health Products Safety, found that the hormonal contraception can increase the risks of meningioma – a mostly non-cancerous tumour – by up to five-fold.
Intracranial meningioma brain tumours can be fatal.
The injection works by releasing progesterone, preventing the ovaries from releasing an egg. It has been previously linked to slight increases in the risk of both breast and cervical cancers.
The research found that the incidence increased from 0.1 per cent to 0.5 per cent among the women who had used the injection in the previous year and had used it for at least a year. It is the first study of its kind to assess the risk of treatments using progesterone in relation to brain tumours.
Prolonged use for more than 12 months was linked with a 5.6-fold increased risk of developing meningioma, the research states.
The newly published study was based on data from the French national health system, and was focused on 108,000 women in France, 18,062 of whom had meningioma surgery between 2009 and 2018.
However researchers said that they only found a correlation between the injection and the risk of brain tumours – not causation.
The research backs up precious findings that linked the progesterone drugs chlormadinone acetate, nomegestrol acetate and cyproterone acetate to tumour growths. The study did not link the pill and implant to increase rates of the intracranial meningioma brain tumour.
Director of research, policy and innovation at Brain Tumour Research, Dr Karen Noble, said the research could open the doors to research regarding preventive measures.
“Any increased understanding of the risk factors of brain tumours is beneficial to the brain tumour community. It may open doors to research on preventative measures, as well as increase our understanding of why these tumours arise in the first place,” she said.
“Although this study has linked certain progestogen treatments to an increased risk of meningioma, it has also demonstrated the safety of other progestogen treatments, which were shown to not increase risk. If you are concerned, it is recommended that you speak to your GP before stopping any prescribed treatment.”
Free contraceptive provision, including contraceptive injections, implants, and the oral contraceptive pill, was expanded by the State in January.
Launched in 2022, the programme has offered free contraception to Irish women, as well as those who “identify as transgender or non-binary.” While it was initially open to those aged 17 to 25, the scheme’s age limit was raised to 30 in 2023, and increased to 31 this year.