Fear of breast cancer related to use of hormone replacement therapy (HRT) remains a barrier to prescribing and use of HRT by healthcare professionals and women respectively. For most women, benefits of HRT when prescribed for treatment of menopausal symptoms outweighs risks such as thrombosis or breast cancer.

Let’s look at a case to illustrate this.

A 50-year-old perimenopausal woman presents with multiple menopause symptoms. She had her last menstrual period 8 months ago and wishes to consider HRT for vasomotor, mood, musculoskeletal and genitourinary symptoms of menopause. She has a body mass index (BMI) of 24 and reports no major previous medical or Gynaecological problems. She has history of appendicectomy in her 20s and has a family history of breast cancer (one of her maternal aunts had an oestrogen sensitive breast cancer at 67 which was treated with surgery and radiotherapy). She does not smoke and does not drink excessive alcohol.

She has tried herbal treatments and supplements so far, but her symptoms have not improved, and she is not keen to take anti-depressant medications. She is keen to take HRT but is worried about the risk of breast cancer and would like to know more.

What are the benefits and risks associated with HRT use?

All medications have benefits, side effects and risks and so does use of HRT long-term^1-4. For most individuals, the increased risks are very small, but it is important that every woman weighs up the risks and benefits for her as an individual. Most HRT guidelines recommend that women should take the lowest effective dose of HRT that controls their menopause symptoms effectively. There is limited data on the use of HRT in women above the age of 70^5,6,7,8,9.

HRT remains the most effective treatment for menopause symptoms. It has been shown to improve quality of life. It has other benefits such as prevention of bone loss and osteoporosis. Starting HRT within 10 years of onset of menopause is associated with reduced risk of future heart disease^6,9. HRT may also have metabolic and cognitive health benefits; however further research is required to confirm these findings.

The main risks associated with use of HRT are:

• Thromboembolic disease (blood clots in veins and lungs) and stroke^5,6,7,8,9,10
• Breast cancer
• Endometrial cancer
• Ovarian cancer and
• Gallbladder disease

Large studies such as the Women’s Health Initiative (WHI) and the Million Women Study (MWS) caused concerns and controversy over the long-term use of HRT when their findings were published 20 years ago¹¹.

However, reanalysis of some of that data and findings from recent studies over the past decade or so have shown that in women who need treatment for menopause symptoms — initiating HRT during perimenopause or early menopause may provide a favourable benefit-to-risk ratio. For most healthy women considering HRT during or after perimenopause – benefits outweigh risks. However, it’s an individual decision whether to use it or not after weighing up the two. Most HRT guidelines recommend HRT at least until the age of 51 (average age of natural menopause) for women with premature or early menopause either for symptom treatment and quality of life or prevention of osteoporosis and cardiovascular disease¹².

How should this woman be counselled about her risk of breast cancer in relation to HRT?

Combined oestrogen with progestogen HRT through any route (oral or transdermal) slightly increases the risk of breast cancer. Oestrogen only HRT (oral or transdermal) is associated with no or minimal increase in risk^8,13,14. A controlled study assessing and comparing the association between different HRTs and breast cancer risk versus HRT never-users, using data from the French E3N cohort study (n=80,377) found risk is a little higher for women who take HRT over the age of 60 and those who take HRT preparations which contain traditional forms of progestogens such as medroxyprogesterone¹⁵, norethisterone¹⁶ or levonorgestrel rather than micronised progesterone or dydrogesterone (which is the progestogen in Femoston range of HRT)^1-4,8. However, the absolute risk of breast cancer remains small at about one extra case of breast cancer per 1,000 women per year on HRT^9,12.

Lifestyle factors such as smoking, excess alcohol intake and obesity have a similar or much greater impact on breast cancer risk as compared to HRT. Women who have a strong family history of breast cancer or genetic risk from breast cancer can have the option of HRT for menopause as most of their risk for breast cancer comes from their elevated background risk due to genes or family history and HRT on top adds minimal risk^9,12. For most women, benefits of HRT for quality of life, bone and heart health outweigh risks of thrombosis or breast cancer.

For women who experience premature or early menopause – there is no additional risk of breast cancer from taking HRT until the average age of natural menopause (51). There is also no added risk of breast cancer associated with vaginal oestrogen therapy. It is important that women discuss HRT benefits and risks unique to them with their healthcare provider so that they can make an informed choice^8,12,13,14.