Prolonged use of hormones may have long-term consequences for women.
A team of researchers led by Alain Weill from French National Health Insurance, found that the long-term use of the hormone drug cyproterone acetate (CPA) is linked to a 7-fold increase in risk of developing brain tumours in women.
CPA is a synthetic progesterone that lowers testosterone levels. It is used to treat prostate cancer in men and for severe acne and excessive hair growth in women. Some birth control pills also contain low amounts of CPA.
In their paper, published in BMJ, the researchers report that women taking a high dosage of CPA (25 or 50 mg/day) for more than five years more frequently underwent surgery or radiotherapy for meningioma, a type of tumour that forms on the membrane of the brain.
The highest group at risk were women who were taking high doses of CPA for 10-30 years, but risk decreased from a year after CPA use was discontinued.
CPA is also used for hormone replacement therapy, and risk of meningiomas also increased for transgender women taking high doses of the drug.
The study was based on observation data from gynaecologists; the researchers examined 250,000 women and girls and 11,000 transgender women, living in France between 2007 and 2014.
The researchers highlight that a limitation of such observational studies is that they cannot clinically prove a direct link, but a strong correlation is nevertheless evident.
Regardless, they assert that the large dataset and correlation requires further research into the health effects of using high doses CPA for more than five years.