Struggling with menopause symptoms? HRT can help – but there are risks to consider. Photo / 123RF
A recent study revealed the link between some types of HRT and rare blood clots. Our experts assess the risks and whether it’s right for you
More women than ever are taking hormone replacement therapy, or HRT.
For many, HRT is life-changing, diminishing debilitating symptoms ranging from hot flushes and brain fog to aching joints and vaginal dryness.
While the increased awareness around menopause and its symptoms is undoubtedly positive, weighing the risks and benefits of HRT is not always straightforward. “Many women find the research around HRT confusing,” says Professor Janice Rymer, a consultant gynaecologist at Guy’s and St Thomas’ NHS Trust and chairman of the British Menopause Society (BMS). “There is still a lot of misinformation out there.”
Hence, we asked the experts to cut through the noise to help us understand the relative risks of each type of HRT, and whether it could be dangerous for our particular set of circumstances or not.
Cancer risk from taking HRT depends on many different factors, including the kind of HRT you take, your age and general health.
In 2002, the Women’s Health Initiative report into the effects of HRT found a statistically significant increase in rates of breast cancer among those taking it, alarming women and triggering widespread panic in the medical profession.
The research has since been widely discredited. “The average age of the women studied was 63, which is not usually when women are prescribed HRT – it’s normally close to a woman’s last menstrual period,” says Rymer.
When only data from women aged 50-59 was examined, the study showed that over five years of taking HRT, there were an additional four cases of breast cancer per 1000 women. However, the type of HRT taken by the women studied was combined conjugated equine oestrogen and medroxyprogesterone acetate, not the body-identical hormones normally prescribed today. The latter are thought to be safer because they are the same structure as the hormones women naturally produce.
Body-identical oestrogen, in the form of tablets, patches, gels and sprays, is now commonly used in combination with “more breast-friendly micronised progesterone [called Utrogestan] which has been shown to have no increased breast cancer risk for up to five years of use”, says Dr Alice Duffy, a BMS-accredited menopause specialist and founder of Health in Menopause, a private clinic in Nottingham. “Beyond that, we lack trial data.”
Vaginal oestrogen, applied locally to relieve symptoms such as dryness, irritation and frequent urinary tract infections, carries no increased breast cancer link.
There is far less research into a possible link with ovarian cancer. One meta-analysis in 2015 showed women who use HRT (either oestrogen-only or combined) for five years from around 50 years of age have about one extra ovarian cancer diagnosis per 1000 users.
The safety of HRT can also depend on a woman’s family history, fitness levels, body mass index and how soon during or after menopause they start taking it. If you have had breast cancer, you’ll usually be advised not to take it.
The NHS puts the overall risk at around five extra cases of breast cancer in every 1000 women who take combined HRT for five years. It states that the risk increases the longer HRT is taken, and the older you are – although there’s no one-size-fits-all figure, as it depends on an individual’s genetics and modifiable risk factors.
The experts emphasise that in healthy women around menopause age, the risk is very low. “The figure [of] five in 1000 extra breast cancer cases on HRT compares with five in 1000 in women who drink more than two units of alcohol per day, and 24 in 1000 in women with a BMI over 30,” says Duffy.
“In women who take two-and-a-half hours of moderate exercise per week, it’s seven in 1000 fewer cases, so lifestyle is extremely important.”
“Heart health is one of the most confusing areas of HRT research for women,” says Rymer. “Different HRT regimes, and the timing of starting them, are very important.”
Last month, a study was published that linked certain HRT tablets containing both oestrogen and progestin, a synthetic form of progesterone, with a higher risk of heart disease and rare but serious blood clots known as venous thromboembolism in women around menopause age. HRT tablets have also been found to slightly increase the risk of stroke.
So how much should women worry about the findings? The British Menopause Society pointed out that the Swedish study was not a randomised controlled trial – “the gold standard” – but an “inherently flawed” observational study of women who had taken HRT.
“We know oral oestrogen can increase the risk of a blood clot or stroke, and this can be further enhanced by the use of oral synthetic progestins,” says Duffy. “When oestrogen is taken by mouth, it is metabolised in the liver which activates the coagulation pathway, resulting in the increased risk.”
Oral HRT is still used in women at low risk of thrombosis, but it is now far more common for women to use transdermal oestrogen in the form of patches or gels, which has no increased risk of blood clots or stroke.
Similarly, the Swedish study showed a link between the combined HRT tablets and a higher risk of heart disease, and between tibolone (a type of HRT that contains a synthetic hormone) and an increased risk of heart disease and heart attack – but women are rarely prescribed these in the UK today.
For women who started taking transdermal HRT within 10 years of menopause, and before the age of 60, no increased risk has been found; in fact, it is likely to be associated with a reduction in coronary heart disease and cardiovascular mortality.
Dr Naomi Potter, the BMS-accredited founder of Menopause Care, says: “In your average healthy perimenopausal woman, it is thought that HRT has a positive benefit on sugar metabolism, risk of diabetes and cholesterol profile, which would indicate that it would have a positive influence on cardiovascular health.”
For women over 60 taking HRT, there is believed to be a slightly increased risk of cardiovascular disease, although the reason is not yet known. The risk is more likely if they have started HRT late into the menopause, and it can depend on the dose and how it’s taken: a lower dose and transdermal HRT lessen it.
“For healthy perimenopausal women, HRT is an extremely safe medication, particularly the transdermal oestrogen and micronised progesterone,” says Potter.
“The risks associated with these are very minimal and are outweighed by the benefits. Some women have extremely debilitating symptoms, which, as well as being distressing, can also have a knock-on effect on other health conditions.”
Many studies have shown HRT to reduce the risk of osteoporosis, a thinning of the bones. The oestrogen in HRT slows down the rate of bone loss and even promotes new bone growth which helps keep bones stronger for longer. HRT also helps maintain muscle strength.
It could also possibly protect against dementia, but the current research is mixed. A 2021 Arizona University study of nearly 400,000 women found that women who took transdermal, body-identical oestrogen and progesterone were 73% less likely to get dementia and other brain-degenerating diseases. Another study, following dementia rates of over 55,000 women, showed the opposite, that HRT increases dementia risk.
Rymer says there’s no hard-and-fast cut-off age after which HRT has more risks than benefits. “It’s vital to have an annual review with patients to discuss any red-flag symptoms or health issues they may be having, the latest research, and what they want from HRT,” she says. “Women need to have access to all the information and decide for themselves what they want to do.”
Duffy agrees, adding: “It’s all about the balance of risks and benefits for the individual – many women will happily incur some risk for improved quality of life, while some will not wish to take any risks. It’s a personal choice.”
The average age of patients in the study was just 38, highlighting risks for younger adults.