The first point is that the quoted study is an amalgamation of selected surveys. Surveys look at common links and can suggest but cannot say that HRT causes cancer and an increase in cancer reporting is not the same as an increased in suffering from cancer. For an example, consider a survey of healthy men going for routine prostate examinations. Those having the exams would be much more likely to be diagnosed with prostate cancer compared to those who never get examined. The headline might be prostate exams increase cancer but it’s clearly absurd to ague that the exam causes the cancer.
To know for definite you need a study where tens of thousands of men are randomly chosen to have a prostate check and the others have a sham examination, then decades later you see how many of those men had been later diagnosed with prostate cancer.
Believe it or not, this type of research has been done for women randomly given HRT or dummy pill. If you are in the mood for selective reporting, the result is that oestrogen HRT significantly reduces breast cancer, as the highest quality evidence shows a reduction in risk. The study reported cannot tell us the risk with any precision and does not add much to our current beliefs but it is plausible and some experts agree with it. The systematic review is an outstanding example of how to amalgamate data and the biases and limitations are honestly expressed in the Lancet publication.
So if you believes that HRT increases the risk of being diagnosed with breast cancer, what does it mean for you?
You could put it into perspective and think that the increased risk attributed to 5 years HRT is less than the extra risk associated being overweight. Take another perspective. There is a simple drug that halves your risk of breast cancer. You are not offered it routinely because a 50% risk reduction is a small overall benefit. This makes a 2% increased risk linked to HRT relatively trivial. This is because it is your overall personal risk that matters, not minor adjustments to added risks. This is why you need your GP to talk you through any risks and decisions to change your HRT prescription.
This is not new news and most GPs are trained in this area. NICE is currently updating their guidance and this study will be added to the enormous database they currently have. Your decision to take HRT is a complex holistic assessment of risks, benefits and uncertainties. The study in the Lancet is good, but will not tell a GP anything they do not already know. If you have any questions at all about the menopause, HRT or your cancer risk, you can ask me on the Ask Eve line, nurse@eveappeal.org.uk.