Menopausal Hormone Therapy (MHT/HRT) and cancer fact sheet

The Cancer Council NSW’s position

  • Based on the international body of evidence, we know that menopausal hormone therapy (MHT) increases the risk of breast cancer
  • As a result, women who use MHT need to be fully informed by their doctor of the risks and benefits
  • MHT should be taken for shortest time possible and only for the treatment of moderate to severe menopausal symptoms
  • Women should regularly review their need to take this medication with their doctor every six months

Menopausal Hormone Therapy (MHT/HRT)

Menopausal hormone therapy (MHT), also known as hormone replacement therapy (HRT) is a treatment using a combination of oestrogen and progestogen or oestrogen-only hormones, to ease the symptoms of menopause that usually occur throughout this stage of a woman’s life, usually in her 40’s and 50’s. These symptoms include hot flushes, night sweats and vaginal dryness.

MHT and breast cancer

The latest research from Cancer Council NSW has found that Australian women who are currently using MHT are at double the risk of being diagnosed with breast cancer than women who have never used the medication.

These findings are consistent with the overwhelming international evidence that the risk of breast cancer increases in women who use MHT. The risks increase with duration of use, so the longer a woman uses MHT the greater her breast cancer risk. We also know that combined oestrogen-progestagen therapy puts a woman at a higher breast cancer risk than oestrogen-only therapy.

How high is the breast cancer risk associated with MHT?

Women who are current users of oestrogen-only therapy (who have been on MHT for around five years) have a 20 per cent increase in the relative risk of developing breast cancer. Use for around ten years leads to a 30 per cent increase in risk. The corresponding risks for women taking combined oestrogen-progestagen therapy are 60 per cent (for five years of use) and 120 per cent (for ten years). However, as soon as women stop taking MHT, their breast cancer risk reduces significantly.

What are the messages for women currently using MHT or who are considering using it?

  • We know that MHT is an effective treatment for the symptoms of menopause, primarily hot flushes, night sweats and vaginal dryness which can significantly affect a woman’s quality of life.
  • However, the risks associated with taking MHT are substantial and include breast and ovarian cancer and stroke.
  • The difficult decision to take MHT is ultimately up to each woman to weigh up the risks against the benefits, with the current evidence at hand and the advice of their doctor.

Where to now?

In Australia, there are currently around 500,000 women taking MHT, 12 per cent of women aged 40-65, and the majority of these women have been taking MHT for longer than five years. This suggests that there is an opportunity for greater awareness of the risks and to encourage shorter-term use and regular review of MHT to reduce cancer-related harm associated with taking these drugs.