For women taking hormone replacement therapy (HRT), it is hard not to worry after new reports of a link found between hormone replacement therapy and breast cancer.
So is this true? And what does this mean for women currently taking hormone replacement therapy?
Let’s start by looking at the research published in the medical journal, Lancet on 29 August 20191.
This paper reviewed data from nearly 570,000 women who participated in 58 studies of hormone replacement therapy, now commonly referred to as menopausal hormone therapy (MHT).
The authors suggest that women had a 30% increased risk of breast cancer if they were using menopausal hormone therapies that contained estrogen-alone, and a doubled risk of breast cancer for combined estrogen and progesterone therapies, compared to women not using menopausal hormone therapy. They suggest that the risks increased further the longer these therapies were used.
So, is this true?
Yes – but most of this information was already known and has already led to changes in treatment.
The majority of the studies included in the review were published more than ten years ago, and many of the types of hormone therapy used by these women are already no longer recommended.
For example, nearly all the women included in the study were using combined estrogen-progestogen therapies that contained the progestogens medroxyprogesterone acetate (MPA) or norethisterone (norethindrone). This was the standard approach to hormone replacement across the USA and UK before the results of the ‘Women’s Health Initiative’ study in 2002 showed they were linked to poor health outcomes2. The use of these medications is now discouraged because of their potential adverse effects on breast cancer risk and heart health.
Before the results of the Women’s Health Initiative study were released, most women in Australia using menopausal hormone therapy were taking estrogen in the form of a tablet. However, this is no longer recommended as it leads to very high blood levels of the hormone estradiol. Instead, estrogen is now taken as a patch or gel administered to the skin, which results in longer-lasting, lower and more balanced hormone levels.
The Australasian Menopause Society (AMS) urges women not to worry.
In a media release in response to this publication3, the society states,
“It is extremely important to note that this paper does not inform us of the impact of current recommended MHT prescribing practices on breast cancer risk”.
Professor Sue Davis, president of the International Menopause Society and recipient of the 2019 ESA Senior Plenary Award, notes that current menopausal hormone therapy regimes are much improved from those of the past.
Further, Professor Davis also stresses the importance of these new therapies on women’s overall health and well-being.
“The only outcome assessed in this review was breast cancer risk. We know that menopausal hormone therapy has a positive effect on other areas of health, such as reducing osteoporosis and risk of fractures, as well as lowering the risk of cardiovascular disease.
“There was also no consideration of other common but serious symptoms that impact on women’s every-day health and ability to function.”
Around 75% (or three in four) of women going through menopause have hot flushes and night sweats. These can be very severe for around 30% (or one in three) women. Other symptoms include difficulties sleeping, pain in joints, tiredness, anxiety, mood changes, bladder changes and vaginal discomfort, especially during sex.
Safety of hormone replacement therapy for women experiencing early menopause
The average age of menopause in Australia is 51 years. About 10% of women experience menopause early – defined as menopause before the age of 45 years.
For women with early menopause, hormone therapies are referred to as hormone replacement therapy rather than menopausal hormone therapy. This is because the treatment is replacing hormones that would otherwise be produced naturally at this age.
Women who experience early menopause have a greater risk of premature death from all causes, including cardiovascular disease4. They are also at greater risk of osteoporosis and fractures. By taking hormone replacement therapy, these risks become the same as women their own age who have not yet reached menopause.
Professor Davis raises a concern with possible confusion of the findings from the recent review for women starting hormone replacement therapy before the age of 45 years.
“In the current paper, the authors report a reduced risk of breast cancer in young postmenopausal women who do not use hormone therapy compared to those who do. This implies the hormone replacement therapy increases their risk.
“What they fail to discuss is that the hormone therapy restores their breast cancer risk to what it would be if they had not gone through early menopause”.
Current recommendations for menopausal hormone therapy
Current menopausal hormone therapies are effective in reducing symptoms and give other health benefits. They are safe to use for most women, but tailoring treatment is essential.
When deciding whether to prescribe menopause hormone therapy, the International Menopause Society recommends doctors consider women in the context of her symptoms and risk-benefit profile. Doctors and patients need to weigh up individual patient risks and benefits when contemplating menopausal hormone therapy.
Women begin menopause at different ages, with varied underlying health risks and experiencing a diverse range of symptoms. There are many different options available, each suitable for women’s different needs.
Your doctor can work with you to find the treatment option that is right for you. Please discuss any concerns you have with your doctor.
About the Author
A/Professor Nicolette Hodyl PhD is the Head Writer for Hormones Australia and has over 15 years’ experience working in medical research. She leads Vertex Health, a consultancy specialising in research strategy and health communication.
The medical content in this article has been reviewed by the Endocrine Society of Australia Medical Affairs Committee, and Prof Susan Davis, an endocrinologist specialising in women’s health and President of the International Menopause Society.
- Collaborative Group on Hormonal Factors in Breast Cancer. Type and timing of menopausal hormone therapy and breast cancer risk: individual participant meta-analysis of the worldwide epidemiological evidence. Lancet 2019.
- Rossouw JE, Anderson GL, Prentice RL, et al. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results From the Women’s Health Initiative randomized controlled trial. JAMA 2002;288:321-33.
- Australasian Menopause Society. MHT and breast cancer risk – Lancet 29 August 2019. http://www.menopause.org.au/about-ams/media-info/1468-mht-and-breast-cancer-risk-lancet-29-august-20192019.
- Muka T, Oliver-Williams C, Kunutsor S, et al. Association of Age at Onset of Menopause and Time Since Onset of Menopause With Cardiovascular Outcomes, Intermediate Vascular Traits, and All-Cause Mortality: A Systematic Review and Meta-analysis. JAMA Cardiol 2016;1:767-76.