"On the other hand, the 3-month injectable contraceptive only contains medroxyprogesterone. This substance can inhibit the ovulation process and make cervical mucus thicker, thus making it more difficult for sperm to fertilize the egg. A study published in The British Medical Journal (BMJ) revealed the effects of using this hormonal contraception, which is associated with an increased risk of developing a rare type of brain tumor. The long-term use of certain medications containing progestogen hormones can increase the risk of meningioma – a tumor that is mostly non-cancerous – by up to five times."

The NHS/National Health Service data from England shows that there are about 10,000 prescriptions for medication each month in England. Long-term use for more than one year is associated with a 5.6-fold increased risk of meningioma. “Although this sounds like a very large risk, it is important to realize that meningioma is rare, and an increase in a rare disease by five times is still a rare disease,” said Paul Pharoah, a professor of cancer epidemiology at Cedars-Sinai Medical Center.

The number increased to 200 in women who have used medroxyprogesterone acetate injections. “This small increase in risk needs to be considered in relation to the benefits of using injectable contraception,” said Prof Pharoah. Progestogen is similar to the natural hormone progesterone. This substance is used to treat gynecological conditions such as endometriosis and polycystic ovary syndrome, as well as menopausal hormone therapy and contraception.

A new study published in the journal The British Medical Journal used data from the French national health system on 18,061 women who underwent meningioma surgery between 2009 and 2018. Each case was matched with five women without meningioma – a total of 90,305 – based on year of birth and region of residence. The researchers found that the long-term use of three progestogens was associated with a greater risk of meningioma.

Other progestogens were examined by researchers from the French National Agency for the Safety of Medicines and Health Products, but they did not appear to increase the risk. Because this is an observational study, the researchers could not determine whether hormone treatment is the cause of the tumors. Scientists noted that, with 74 million injection users worldwide, “the number of meningiomas caused may potentially be high” in countries where injectable contraceptives are commonly used. Further research using other data sources is essential to better understand the risks.