As a freshly minted doctor in the early 1990s, I attended lectures describing hormone replacement therapy – which is now known, in this context, as MHT, menopausal hormone therapy – as close to a miracle cure-all. Women shouldn’t worry their pretty little heads, it was implied at the time, because doctors knew best – and this treatment would not only make them feel fantastically sexy, but prevent cardiovascular disease and strokes. Promotion, back then, went beyond recommending it for menopausal symptoms. It was the elixir of life, preventing future illness and making women look younger.
Let’s sidestep the sexist and ageist undertones of that era, and fast forward to the publication of the Women’s Health Initiative study in 2002, which found that the treatment increased the risk of breast cancer. For every 10,000 person-years of combination menopausal hormone therapy use (oestrogen plus progesterone), there were seven more heart attacks, eight more strokes, eight more blood clots on the lungs, and eight more invasive breast cancers. In the ensuing years, the amount of menopausal hormone replacement being prescribed fell by half.
In November 2015, the National Institute for Health and Care Excellence (Nice) published new guidance on treating the menopause. In a press release, it suggested that menopausal hormonal treatment was being underprescribed, and GPs needed to prescribe it more. “For the last decade, some GPs have been worried about prescribing HRT, and women worried about taking it …” it wrote. “For health professionals, the guideline should boost their confidence in prescribing HRT, having fully discussed the woman’s individual circumstances with her.”
That seemed pretty clear, but now a new UK study apparently shows that the risks of breast cancer have been underestimated and “nearly tripled” when women were taking hormone treatment for menopause.
So should I still feel confident about prescribing it? Is this a high or a low risk? Is it a risk worth taking? Well, that depends on the patient. There will be women who regard the risks as reasonable because they experience such enormous benefits. Then there are other women who would consider a much smaller risk of serious harm unacceptable. Autonomy rules, and there is no “correct” answer (although I suspect the General Medical Council would be quick to hold doctors to account for what was viewed as reckless prescribing). But to make that autonomy meaningful, we have to be able to make a rational, informed choice. That needs quality data. So what does the latest study tell us?
It’s a prospective, cohort study, which specifically looked for hormone use and age at menopause, which many other studies have not. Just over 39,000 women had their age at menopause documented, and 775 of these developed breast cancer. They found that the women who used combination MHT were more likely to develop breast cancer by a factor of 2.7; this risk dissipated when the women stopped the MHT, but rose the longer it continued.
The NHS offers detailed decision aids for treatments for everything from arthritis to angina – but none on the menopause
We need to put this into context: 2.7 times a small number is still a small number, so you need to know what your risk was to start with. For a woman aged between 50-70, the risk of breast cancer is about 5%. Is an increase to about 13% for the years a woman is taking the hormones worth it? I don’t know. But I am also concerned as to whether this cohort are truly representative of the population at large, because the women who volunteered for this study were not asked to participate randomly, but were recruited through newsletters sent out by a breast cancer charity. They may, therefore, have been more likely to have a family member with breast cancer, or share the same environmental risks as friends with breast cancer, and so faced a higher risk to start with.
I also don’t reliably know how much the change in breast cancer risk is per woman: as one of the authors, Dr Michael Jones, told me: “Our results are internally consistent and we can talk about relative changes, but we cannot make external extrapolations in absolute risk to the whole UK.” In other words, care is needed – and we will need this data to be replicated in other data sets before we can be confident that it applies equally to other women.
Uncertainty is a hallmark of medical decision making. If a woman develops breast cancer while taking MHT, no one can be sure whether it would have happened in any case. We need context. We can’t control our genes, but what other risk factors can we at least partially control? Cancer Research UK says that 9% of breast cancers are linked to obesity, 6% to excess alcohol, and 3% to insufficient physical activity. In context, MHT is linked to 3% of all breast cancers. If this has been underestimated, as the new study claims, by up to 60%, that means that up to 5% of all breast cancers could be linked to MHT. But there are so many ongoing uncertainties that I think pinning it down to the last percentage point makes this look more accurate than it is.
So what do we do in the meantime? GPs are under enormous pressure anyway – each of our appointments is just 10-12 minutes long, with an average of 2.5 problems being discussed, so there’s barely time to make a safe diagnosis, never mind discuss most of the side effects for each possible treatment. There has been a quiet revolution in medicine in the last decade, a realisation that making choices is often hard to do well. There are now a wealth of “shared decision aids” online, based on high-quality evidence and with the emphasis on assisting patients, not dictating “choice”. They work in different ways; some are online or DVD-based, and they usually try and lay out the pros and cons of treatments in a logical way, giving the person enough time and information to make high-quality decsions.
These have been shown to help people make better decisions about treatment choices – and using them before or after GP appointments is a useful way of making oneself surer of healthcare choices.
The NHS has a website devoted to detailed decision aids for treatments for everything from arthritis to angina – but none, so far, on the menopause. Nice does have an information section on its website about the pros and cons of hormone treatment for menopause, but doesn’t provide any numbers about the risks – or define what they mean by “low-risk”, in common with other US decision aids – and while that might be enough information for some women, it’s unlikely to be detailed enough for others.
We need better quality information that doesn’t offer more certainty than we actually have: we are in a new era of medicine, and honesty about the knowns and unknowns, and the limitations of our knowledge is essential. I will continue to prescribe MHT, but when it comes to discussing risks and benefits, I suspect I will be answering many questions with an honest “I don’t know”.
When it comes to menopausal hormone therapy, women are left guessing at the risks | Margaret McCartney
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