HRT (Hormone Replacement Therapy) and Breast Cancer Risk
HRT has been used for over 50 years, to help women manage their symptoms of menopause. These symptoms occur due to a reduction of oestrogen production from the ovaries, which occurs naturally as women get older, or through surgical removal of the ovaries. HRT has many benefits which can significantly improve the physical, psychological and social health of many women during and after the menopause.
The short and long-term benefits, side effects and potential cancer risks have been studied extensively. This includes whether the use of HRT confer any increased risk of developing breast cancer in those who are taking or have taken HRT.
There have been some very large studies which have followed the health of women in their 50’s and 60’s over 20 or more years and has included those who have taken HRT. The best-known studies include :
“The Million Women Study” MWS (a UK based observational study which followed 1.3 million women age 50-64 between 1996 and 2001) and “Women’s Health Initiative “ WHI (a US based long term on-going study commenced in 1993 and focused on health aspects of postmenopausal women age 50-79 including how menopausal HRT affected the risk of breast cancer) and “E3N Cohort” (a French based study looking at the relationship between menopausal HRT, mammographic breast density and breast cancer risk).
Early publication of results from the MWS suggested the use of menopausal HRT caused an increased risk of breast cancer which left patients anxious to take, (and doctors reluctant to prescribe) HRT. As a result, the use of HRT in the early 2000’s fell significantly. Following this, other publications refuted these findings, and this has left doctors and patients alike to be confused about the actual risks. Currently it is thought that there is a slight increase in the risk of breast cancer in women taking menopausal HRT but that this risk is dependent on several factors ,including
- the type of HRT
- dose
- age when HRT is started
- how long it is taken
- a personal or family history of breast cancer
The Type of HRT:
- Oestrogen only (which can only be used in women who have had their womb/uterus removed). It is thought that there is no increased- or only a very slight increased-risk of breast cancer in women using oestrogen-only HRT .
- Combined HRT
This type of HRT contains both oestrogen and progestogen and this type must be used if the woman still has a womb/uterus. It is thought that the progestogen in HRT is mainly responsible for the increased breast cancer risk as it causes cells to divide. This type of combined HRT is associated with a slight increase in breast cancer risk. There may be a lower risk with newer micronised types of progestogens. It can be taken either continually or with intermittent progestogen;sequentially. Taking it continually is associated with a slightly higher risk of breast cancer.
- Vaginal oestrogen preparations
These have not been shown to increase the risk of breast cancer.
Age at Starting HRT:
Starting HRT at a younger age (50-60) is associated with a lower increased risk of breast cancer than starting it when older.
How long HRT is taken for:
It is thought that the risk of breast cancer is increased the longer the HRT is taken. However, the increase in risk is only slight in the first 5 years. The NHS states that there are around 5 extra cases of breast cancer in every 1000 women who take combined HRT for 5 years.
In Summary :
The relationship between menopausal HRT use and increased breast cancer risk is continually being evaluated and it is important to remember that some lifestyle factors such as obesity and alcohol consumption will have a higher impact on an individual’s breast cancer risk than taking HRT. The association between combined HRT and breast cancer risk is small and it is recommended that HRT should not be used long term. Many women get substantial physical, psychological and social benefits from menopausal HRT. All women should be breast aware, know how to check their breasts,the changes that should be reported and should attend all screening mammograms.