An injectable contraception used by women in the UK has been linked to an increased risk of a type of brain tumour.

A study, published in the British Medical Journal (BMJ), found people using injectable medroxyprogesterone acetate for more than a year appear have a higher risk of meningioma – a tumour of the membranes covering the brain and spinal cord.

It is usually benign but can cause serious problems in some patients due to its location in and around the brain and spinal cord.

Symptoms of meningioma include:

  • Change in vision
  • Hearing loss or ringing in the ears
  • Loss of smell
  • Headaches
  • Memory loss
  • Seizures
  • Weakness in arms or legs

Your Local Guardian: Symptoms of meningioma include headaches, seizures and loss of smell, memory and hearing.Symptoms of meningioma include headaches, seizures and loss of smell, memory and hearing. (Image: Getty Images)

Contraception medroxyprogesterone acetate linked with increased risk of brain and spinal cord tumour

The new study linked some types of progestogen (similar to the hormone progesterone) to an increased risk of meningioma, though several types are not used in the UK.

However, it found that prolonged use of medroxyprogesterone acetate was “associated with an excess risk of intracranial meningioma”.

NHS prescription data suggests there are around 10,000 prescriptions for medroxyprogesterone acetate every month in England.

The new study used data from the French national health system looking at 18,061 women (average age 58) who underwent meningioma surgery from 2009-18.

Each case was then matched to five control women without meningioma (total 90,305) by year of birth and area of residence.

The results showed that prolonged use of medroxyprogesterone acetate injection was associated with an increased risk of meningioma.

Your Local Guardian: A study published in the British Medical Journal has linked prolonged used of medroxyprogesterone acetate to increased risk of meningioma.A study published in the British Medical Journal has linked prolonged used of medroxyprogesterone acetate to increased risk of meningioma. (Image: Getty Images)

Professor of cancer epidemiology at Cedars-Sinai Medical Centre in the US, Paul Pharoah, said that while many of the findings in the study did not relate to UK prescriptions there were risks around medroxyprogesterone acetate.

He added: “The authors note that causality cannot be determined in an observational study such as this but, given what we know about the risk factors for meningioma, it seems quite likely that the association reported for medroxyprogesterone acetate is causal.

“It is important to note that progestogens are an important component of many types of birth control pill (oral contraceptives) and hormone replacement therapy but there are many different types of progestogens and no association with meningioma was found for the types of progestogens commonly used in the United Kingdom.

“This means that women taking the commonly used birth control pills or hormone replacement therapy are not at increased risk of meningioma.

“It is important that women do not stop using their birth control pills without consulting their doctor.

“The notable exception is medroxyprogesterone acetate (also known as Depo-Provera) which is sometimes used as an injectable form of contraception in the UK.”

Prof Pharoah said around 40 out of 10,000 30-year-old women in the UK would be expected to be diagnosed with a meningioma before the age of 80.

“This increases to 200 in those who have used medroxyprogesterone acetate,” he added.

“This small increase in risk needs to be considered in relation to the benefits of using an injectable form of contraception.”

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UK manufacturer of medroxyprogesterone acetate "aware of this potential risk"

Pharmaceutical company Pfizer manufactures two medroxyprogesterone acetate injections used in the UK – Depo-Provera and Sayana Press.

The company said in a statement: “Patient safety is Pfizer’s utmost priority. We ensure rigorous and continuous monitoring of all of our medicines, including the assessment of reported adverse events, in collaboration with the European Medicines Agency and health authorities in each country.

“We are aware of this potential risk associated with long-term use of progestogens and, in collaboration with regulatory agencies, are in the process of updating product labels and patient information leaflets with appropriate wording.”