Mammography involves taking X-rays of the breast, in an effort to detect breast cancer earlier, with the hope that treatment will be more effective. It’s an approach that appears to make eminent sense. Yet, objective study of mammography shows that it doesn’t work so well. For a start, many, many women have to undergo screening for one to have her life saved due to early detection. Plus, mammography leads to a lot of women having further investigations and treatment for harmless lumps and even bona fide cancer that would not have bothered them if it were left alone.
In September, I wrote about some recent evidence which asked serious questions about the effectiveness of mammography, as well as the problems of over-investigation and over-treatment. Here’s an extract from this blog post.
If 2,500 women aged 50 were screened with mammography, only ONE will avoid dying of breast cancer. Now, many of these women (as many as 1000) will have to endure the potential stress of being told by their doctors that there’s something suspicious on their mammogram. And about 500 of these will go on to have a biopsy – an invasive procedure around which there is usually considerable anxiety. As a result of biopsy, it is estimated that between 5 and 15 women will be treated unnecessarily for a condition that was never going to bother them.
This week saw the publication of a study which argues for extension of the mammography programme here in the UK [1]. Currently, women aged 50-70 are invited for mammography every three years. But the study in question argues that it should be offered to women aged 40-49 deemed to be at moderate or high risk of breast cancer because of a positive family history of this condition.
This study has received widespread coverage, and almost all of it has been very positive. See here for an example. You’ll see here that the lead investigator of the study, Professor Stephen Duffy, estimates that extending screening to these women in the form of annual mammograms would save about 50 livers a year. But according to the article, about 300,000 women would be eligible for this screening. Let’s do some maths. If 300,000 women need to be screened each year to save 50 lives, then 6000 women need to be screened to save one life.
I’m not glib about any life saved. But even the most enthusiastic promoter of mammography would surely have to concede that these figures indicate a poor return on investment. The obvious question is if the money and resources pumped into mammography might be better spent elsewhere.
Read the article that I’ve linked to and you’ll see that Professor Duffy claims that extending mammography would give many women peace of mind. That might be true. But what is not mentioned here is the fact that, for many women, having mammography and waiting for the result is inherently stressful. And, as is often the case with those who vigorously promote mammography, no balance is given by reference to the women who have unnecessary biopsies or other investigations. And no mention is made, either, of those women who would end up undergoing potentially devastating treatment for something that would never have brought significant harm to them if left alone.
This morning at breakfast I was having a conversation with a friend and colleague about something unrelated to mammography: cholesterol. I was putting forward some of the counter-arguments to the idea that cholesterol causes heart disease and that reducing cholesterol is inherently beneficial to health. Some doctors seem to get very agitated to hear these opinions even expressed. I have sometimes asked such doctors why they have an issue with people hearing some of the contradictory evidence. Why should patients not hear the other side? The most common answer I get is that “it confuses them”. That may be the case, but that in my view is simply not a good enough reason not to tell people the truth. And in reality, I don’t think patients are as easily confused as many doctors think. For instance, after hearing the contradictory evidence regarding the cholesterol hypothesis, practically everyone I’ve ever met appears to be in no doubt about how seriously they should take their ‘elevated’ cholesterol.
When, in medicine, we only present one side of the story, we rob our patients of the ability to make truly informed decisions about their treatment, and I think this is inherently wrong. I’m obviously never going to have mammography myself, but I do believe that women have the right to know all the facts about this procedure. Listen to people like Professor Duffy and you’d imagine that women who refuse mammography have taken leave of their senses. But as the research I wrote about in September demonstrates, many women would decline mammography end up be significantly better off.
References:
FH01 collaborative teams. Mammographic surveillance in women younger than 50 years who have a family history of breast cancer: tumour characteristics and projected effect on mortality in the prospective, single-arm, FH01 study. The Lancet Oncology 18 November 2010 [epub ahead of print]
