Does HRT cause breast cancer?
Taking HRT increases the risk of breast cancer.
- The longer you use HRT, the greater your risk
- Once you stop taking HRT, it can take up to 10 years for this risk to fall to about the same as if you had never taken it. This will depend on the type of HRT and the length of time you were using it
- Breast cancer risk is greater with combined HRT (which contains oestrogen and progestogen) than with oestrogen-only HRT
Talk to your doctor when deciding to start or stop taking HRT, or if you are worried about HRT and breast cancer.
How much does HRT increase risk?
The risk of developing breast cancer between the ages of 50 and 69 is around:
- 63 in every 1,000 women who have never used HRT
- 83 in every 1,000 women who use combined HRT for five years from the age of 50
- 68 in every 1,000 women who use oestrogen-only HRT for five years from the age of 50
Oestrogen-only HRT increases the risk of womb cancer, so is generally only offered to women who have had their womb removed (hysterectomy).
Tibolone (Livial) is another type of HRT that contains a steroid that acts like oestrogen and progesterone. Tibolone users also have an increased risk of breast cancer, but probably less so than combined HRT users.
Why does HRT increase breast cancer risk?
HRT helps relieve menopausal symptoms by increasing oestrogen levels.
It’s not fully understood why HRT increases the risk of breast cancer, but research indicates that the higher levels of oestrogen help some breast cancers to grow.
Should I take HRT if I have a family history of breast cancer?
If you have inherited the faulty breast cancer gene BRCA1 or 2, speak to your family history or genetics specialist before using HRT.
Benefits and other risks of HRT
Many women decide the benefits of taking HRT outweigh the risks.
While HRT increases breast cancer risk, it also helps to relieve many women’s menopausal symptoms. It can also reduce a woman’s risk of developing osteoporosis (weak bones) in the short term and improve muscle strength.
It has some side effects such as headaches, feeling sick and breast tenderness. These usually happen in the first few months. Taking HRT also slightly increases the risk of having a blood clot or a stroke, and might slightly increase the risk of ovarian cancer.