A recent study regarding breast cancer and HRT has been cause for concern. But some experts say the study is not that straightforward, writes Lorna Siggins
Headlines and medical research findings rarely quite fit, and no more so than when it comes to subjects like breast cancer risk and hormone replacement therapy (HRT).
So when a study published in the prestigious medical journal The Lancet prompted adverse headlines in late August about the association between breast cancer risk and HRT, many family doctors anticipated a busy few weeks ahead.
Public reaction wasn’t quite as strong as it had been after the release of previous research on HRT and associated risk of breast cancer diagnosis. However, Irish Menopause Society (IMS) president Dr Barbara O’Beirne says the findings will be discussed at its annual symposium in Dublin on November 9.
Both Dr O’Beirne and one of her key guest speakers, recently retired London-based breast cancer surgeon Jo Marsden, believe the Lancet paper has raised a “lot of unnecessary concerns” amongst healthcare professionals.
The study by the Collaborative Group on Hormonal Factors in Breast Cancer, published in late August, analysed data from 58 studies around the world on more than 108,000 women who had developed breast cancer after taking what the authors prefer to describe as menopausal hormone therapy (MHT).
The main findings were, firstly, that risk of breast cancer diagnosis is greater with combined (oestrogen plus progesterone) HRT than with HRT consisting of oestrogen alone; and, secondly, that risk of breast cancer remains elevated for more than ten years after discontinuing HRT. This second finding appears to be dependent on the duration of prior HRT use.
Thirdly, the study found that women with an early onset of menopause who started using HRT between the ages of 40 and 50 have an increased breast cancer risk.
It also found that HRT does not have an “additive” effect on risk in post-menopausal women who are obese – their risk being elevated by the extra oestrogen produced in adipose, or fat tissue.
A joint response issued by Britain’s Royal College of Obstetricians and Gynaecologists (RCOG) and the British Menopause Society (BMS) said the overall findings were in keeping with Britain’s National Institute for Health and Care Excellence (NICE) “Menopause Guidance”.
The NICE guidance “notes a small increased risk of breast cancer associated with HRT”.
In the joint statement, RCOG vice-president Prof Janice Rymer said that “women and doctors should be reassured that the findings of this study do not add anything new in terms of the effects of HRT” “Research shows that, for most women, HRT helps to manage menopausal symptoms and is safe,” she said.
Marsden, who is on the BMS medical advisory council, concurs. She points out that The Lancet study’s first main point - that the breast cancer risk is greater with combined HRT, compared with oestrogen-only HRT - is “not new”.
She also points to an important finding in The Lancet paper, which was not publicised: local, or topical oestrogen therapy for the management of symptoms linked to vulvo-vaginal atrophy – as in vaginal dryness – does not appear to increase breast cancer risk.
“The main findings of this collaborative re-analysis in The Lancet omitted evidence from gold standard placebo-controlled studies,” she says, noting that about half of the data used to support the findings was from Britain.
She recalls that the British-led “Million Women Study” was widely criticised at the time of its initial publication in 2003. Among concerns raised was the strong likelihood that women had undiagnosed breast cancer at study entry, leading to “the erroneous conclusion that HRT increases within six months of its initiation”.
“This is not biologically plausible,” Marsden says.
The second key issue raised by the new Lancet study - the risk of developing breast cancer more than ten years after stopping HRT - is a new finding, Marsden says.
However, she cautions that “if you look at the figures for women who have taken any type of HRT for less than five years and stopped more than ten years previously, there are between 31 to 35 cases of breast cancer diagnosed per 1,000 women previously exposed”.
“This compares to 26 cases of cancer among women who have never taken HRT,” she says.
“ Most breast cancers take years to grow to a size where they can be diagnosed, and it is thought HRT can speed their growth,” she explains.
“ When HRT is stopped, these cancers still continue to grow, but at a slower rate. This means they will take longer – as in many more years - to reach the size threshold for diagnosis. This could explain the finding in the Lancet paper,” Marsden says.
On the study’s third key point - the risks posed to women who took HRT earlier due to earlier onset of menopause- Marsden says that the researchers were not comparing “like with like”.
“Younger women with an early menopause taking HRT in this study were compared with women of a similar age who had an early menopause but were not taking HRT. It is well established that the latter group of women have a reduced risk of breast cancer,” she says.
“ The appropriate women to make a comparison with would have been those of a similar age who were still having menstrual periods,” she says.
In light of this, she believes it would be “inappropriate” to change the current recommendation on years of HRT exposure in women with a premature menopause.
That exposure should still be counted from the age of 50, which is the age most women experience the onset of menopause, she notes.
So is there a safe dose of HRT?
“To date, there is no strong clinical evidence to support a dosage effect of HRT,” Marsden stresses.
“ For some women, management of menopausal symptoms is their main priority,”she says. “For others, longer-term use of HRT to reduce the risk of osteoporosis and fragility fractures is a justified significant priority.”
Both Dr Marsden and Dr O’Beirne stress that lifestyle factors, such as obesity and excess alcohol pose a far greater breast cancer risk.
Dr O’Beirne believes the benefits of HRT, taken in consultation with a doctor, still far outweighs the risks when women have such difficult symptoms of menopause that it affects their quality of life.
Such benefits include bone and cardiovascular protection, she says, at a time of life when women are at risk from both cardiovascular disease and osteoporosis.
“Healthy lifestyle changes are good for all, but cognitive behavioural therapy and reflexology are suitable options for those unsuited to, or opposed to, taking HRT,” Dr O’Beirne says.
There are other treatments which can be prescribed for those who cannot or don’t wish to take HRT. Homeopathy, including reflexology and acupuncture, are also beneficial, as are some herbal remedies.
However, Dr O’Beirne warns that certain products may interact with other medications, and online products from unregulated sources should be avoided.