A new study in the BMJ has been roundly misreported by the press. What is it actually saying?
By Dr Ornella Cappellari
Breast cancer is the most common type of cancer in women in the UK. And although treatment is becoming increasingly effective, being diagnosed with it is still both frightening and dangerous. Prevention is paramount. In light of the recent report in the BMJ, let’s take a look at the real relationship between HRT, breast cancer and the menopause.
Usually, the incidence of breast cancer in women increases after the age of 40. Also, after 40, menopause is getting closer – and with it, the decision whether or not to use HRT. Hormone replacement therapy is a game-changer not just in the treatment of menopausal symptoms, but also because it can prevent a number of diseases that arise in menopause due to lack of oestrogen.
The benefits of HRT are many and varied: it’s a huge help for those experiencing serious symptoms, and an excellent form of prevention against a number of conditions for the majority of women. HRT can prevent the onset of cardiovascular disease, osteoporosis, dementia and many other conditions. Over the decades, however, many studies have concentrated on one very common question: does HRT increase the incidence of breast cancer?
There are many factors to take into account when attempting to answer this question. It is worth noting that even in the best studies undertaken on HRT and breast cancer, it is difficult to avoid bias, especially in those in which the period of exposure (in this case, HRT use) overlaps with the period of risk (breast-cancer incidence).
All the studies we have seen in recent years have had some form of difficulty or bias. There are lots of variables that make them tricky to carry out. Recently, a paper was published in the BMJ – a large statistical analysis in a nested case-control study – demonstrating that taking HRT, and especially combined HRT, increases the probability of getting breast cancer.
The media coverage of this paper has been deeply misleading, and in some cases, factually incorrect. Some newspapers stated that HRT causes breast cancer. This is not true. And it is not what the BMJ research paper set out to demonstrate. There is evidence that HRT can, in certain circumstances, increase your likelihood of developing breast cancer, but it has been never proved, for example, that HRT increases the risk of death from breast cancer. There are other factors – such as obesity, smoking and not being physically active – that are just as significant as HRT.
The BMJ paper also used a nested case-control study (NCC), rather than the gold standard in research, the randomised case-control study (RCC), which randomly assigns participants into different experimental or control groups. The only expected difference between the control and experimental groups here is the outcome variable being studied, which eliminates any possible bias within the population.
For the BMJ study, not having used the gold standard represents a weakness. But even if the experimental design wasn’t optimal, the data obtained from this study is very similar to much that has already been published. So, what can we learn from this study compared to others?
If this particular paper is interpreted correctly, it shows results in line with other studies, with lower risks for long-term users of HRT. Let’s look at what the studies tell us.
Younger women and HRT
Women taking HRT under the age of 51 (the average age of menopause) have no increased risk of developing breast cancer. This is because younger women taking HRT are replacing the hormones their body would otherwise produce. It’s essential that they are made aware of this; in fact, if younger women don’t have the correct type of HRT, they have an increased risk of developing osteoporosis and cardiovascular disease. HRT greatly reduces these risks.
Combined HRT
Some studies show that taking combined HRT (HRT containing both oestrogen and a progestogen) could be associated with a small increased risk of breast cancer. However, the media has misinterpreted this information and presented the risk as being greater than it is. As the studies described, the increased risk lies with the type of progestogen in the HRT.
Micronised progesterone (body-identical progesterone) is not associated with an increased risk of breast cancer in the first five years of taking it. After five years, the risk of breast cancer is very low – and lower than the risk associated with the older types of progestogen.
The level of increased risk of breast cancer in women taking the older types of combined HRT, however, is similar to that of any woman if she is overweight or drinks around two glasses of wine a day.
The BMJ study, as well as a Lancet study from September 2019 (you can find it reviewed here) notes the importance of personal history, correct dosage and regular check-ups.
Neither of these papers, however – which are the most recent on the subject – stresses one very important thing: the benefits of HRT. HRT is a drug, and every drug has side effects. The new HRT formulations are very safe – in both papers, the increased risk is found to be very small compared to the benefits HRT brings. In fact, in most women, the benefits outweigh the risks in HRT therapy. Quality of life needs to be taken into consideration, too.
Ask your doctor or menopause specialist for more information so you can make the most informed choice on your treatment.