‘Independent review’ confirms that mammography is inefficient and harms more women than it helps

For some years now there has been quite a raging debate regarding the effectiveness of mammography, and the politics surrounding this screening strategy. I’m polarising things a bit here, but in the two camps on either side of the debate have been:

1. those whose view appears to be that mammography is a no-brainer, and that women who don’t have their breasts examined need their heads examined.

2. those who argue that mammography is not very effective at saving lives, and exposes many women to investigations and treatment for cancers that would never have bothered them during the natural course of their lives (termed ‘over-diagnosis’).

I should declare that I am in the latter camp. My real objection to mammography is not so much the procedure itself – it’s the fact that, for the most part, women are generally not given the facts and therefore are disabled in terms of their ability to make an informed choice about whether they have mammography or not.

The controversy around mammography has been swirling long enough and hard enough for an ‘independent review’ to be conducted. Professor Sir Mike Richards (National Cancer Director in England) and Dr Harpal Kumar (CEO of Cancer Research UK) asked Professor Sir Michael Marmot to assemble and chair a panel to review the benefits and harms mammography. The panel took evidence from trials as well as expert opinion. The results are in and were published this week in the medical journal the Lancet [1].

The panel accepted the weaknesses of the evidence and the fact that the studies were done a long time ago, but concluded that (in its opinion) mammography reduces risk of death from breast cancer is reduced by about 20 per cent over time.

This 20 per cent figure represents what is known as ‘relative risk reduction’. But the benefits in real terms (known as ‘absolute risk reduction’) are dependent on how much risk there is in the first place. Relative risk reductions most meaningful when overall risk is high. Fortunately, the review panel crunched the numbers in a way which allows all of us to get a better idea of how effective (or ineffective) mammography is in reality.

According to their calculations looking at a range of evidence, if 10,000 women aged 50 were invited to screening for the next 20 years, 43 would be prevented from dying from breast cancer. 10,000 divided by 43 = 233. So, 233 women would need to be invited for screening for 20 years to prevent one breast cancer death. Not all women attend when invited, and it turns out that 180 women would need to be screened for 20 years to prevent one breast cancer death. Screening in the UK is scheduled every 3 years, so lets multiply 180 by 6 (the number of screenings a woman will have in 20 years) and we have a total of 1,080. So, according to these stats, more than 1,000 mammograms have to be performed for one life to be saved from breast cancer. I suspect most women (or men) if asked would never imagine that mammography is, overall, a very inefficient way to save lives.

It is perhaps worth bearing in mind that some evidence paints an even gloomier picture of the effectiveness of mammography. One study from the respected Cochrane group of researchers published last year estimated (based on what the researchers believed to be the best evidence) that the number of women needed to be invited to screening to prevent one breast cancer death was in the order of 2,000 [2]. Other reviews have found numbers needed to be screened to prevent one death from breast cancer of 720 and 400).

But going with the recent expert panel’s more optimistic data, what this all boils down to is that even after 20 years of screening, only about half a per cent of women benefit from mammography.

Against this, of course, we need to put the risk over-diagnosis. The panel puts this at 129 women per 10,000 invited to screening. That is precisely 3 times the number who, they calculated, have their lives saved.

There are other hazards to mammography, in particular the emotional stress (and discomfort) associated with having the procedure and further investigations. The impact of these things is difficult to quantify, but I suspect tips the balance even further in favour of those in camp 2 (see above).

But one good thing that has come out of the debate and this review is this: it appears there is now going to be most honesty and transparency about the relative ineffectiveness of mammography as well as its very real hazards. That way, women will be able to make much more informed choices about whether to subject themselves to this procedure. Now that more facts will be made available to women, something tells me that growing numbers of women are going to take the view that mammography is not a no-brainer after all.

References:

1. Independent UK Panel on Breast Cancer Screening. The benefits and harms of breast cancer screening: an independent review. Lancet 30 October 2012

2. Gotzsche PC, et al. Screening for breast cancer with mammography. Cochrane Syst Rev 2011;1:CD001877

23 Responses to ‘Independent review’ confirms that mammography is inefficient and harms more women than it helps

  1. Liz 2 November 2012 at 1:24 pm #

    Having been diagnosed by mammogram with breast cancer, I’m not sure what I think about this. neither I nor the specialists could feel a lump. It was a lobular cancer, which tends not to create a lump, but more often causes a thickening of the tissue, so without the mammogram, it could have grown much larger, and perhaps been more likely to spread to other parts of the body before I would have got a diagnosis. So I’m sorry for mental trauma that people who get wrongly diagnosed with cancer go through, but personally, I’m quite glad to have, hopefully, a better chance of staying alive for longer as a result of going for a mammogram!
    Do tell me if I’ve missed something in my thinking.

  2. Kirsteen 2 November 2012 at 1:37 pm #

    I am 61 and have never believed in mammograms. 18 months ago, I was diagnosed with aggressive breast cancer. I had a radical mastectomy, chemo and herceptin and have been told it’s high risk of returning. I am now expected to have a mammogram every year, which I still don’t want. I don’t see the point in all the extra radiation. However, I’m finding it hard to find any data or put together a concrete argument for someone in my position. Any ideas gratefully received

  3. audrey wickham 2 November 2012 at 1:48 pm #

    A neighbour of mine, an academic at Sussex University, died from breast cancer. When I said at the time “but surely you had a mammogram” – she said she had a mammogram six weeks before the lump in her breast was diagnosed and there had been nothing showing on the film. Whichever way one plays it there is uncertainty.

  4. Dr John Briffa 2 November 2012 at 2:08 pm #

    Liz

    Actually, the percentage of women who have cancers detected via mammography and then have successful treatment who actually hav had their life saved is much smaller than I think we imagine. See the post below for more on this:
    http://www.drbriffa.com/2011/11/15/when-mammography-detects-cancer-which-is-successfully-treated-has-mammography-saved-that-womans-life-probably-not/

  5. Margaret Wilde 2 November 2012 at 3:54 pm #

    Hi Kirsteen

    I completely agree with your viewpoint and I am against mammograms myself. The Radiation Chart on this webpage http://www.informationisbeautiful.net/visualizations/radiation-dosage-chart/ shows how very high the ionising radiation is for a mammogram. Maybe it would assist you in your arguments about the desirability of yearly mammograms for you.

  6. Sandy Angove 2 November 2012 at 6:13 pm #

    Any views on thermography? A friend in Australia mentioned it to em as a better alternative to mammography

  7. Wiz 2 November 2012 at 7:46 pm #

    I had a mammogram on Tuesday, no mental trauma and no physical discomfort. I arrived at 2.40 pm and was out by 2.50 pm. Personally, if 1000 – 2000 women have to have a mammogram to save one life I think it is something worth doing. Especially if its my life that is saved. Would I want my mother, sister, daughter to have one – of course. Screening is not perfect and not a substitute for self examination but I am glad I attended for my mammagram and I will be attending again in 3 years.

  8. Dallee 2 November 2012 at 8:09 pm #

    Here in the US, the last scientifically supported recommendation was to have mammography at 2 year intervals for the general population, which accords with what I have been doing for many years before that report came out. Oddly, my internist (a generally up-to-date very fine doctor) was unaware of that recommendation; the staff at the mammography center dismissed the recommendation, saying that there were no “breast specialists” on the panel that made the recommendation.
    My experience just indicates to me that it can be very hard for some of these objective reports to gain general acceptance — especially with all the money poured into “pink washing” and publicity (and very plush salaries and perks at high-visibility charities).

  9. Ginny 2 November 2012 at 9:21 pm #

    Not sure yet what I think about mammograms but I guess I’m leaning on the side of not getting one. I’m overdue a couple years for one, which my doctor frowns on, especially since I’m high risk being the only woman in my family left who hasn’t had it. My sister, who died of breast cancer, was found with a stage 4 lump that had already metastasized, 3 mo. after having a mammogram which found nothing. We even suspect the mammogram may have caused it to metastasize, but can’t prove that. For now I do a self-check, and do all I know to do nutritionally to prevent it, such as a healthy low carb diet. So far in my family I’m past the age all others have gotten it.

  10. Cybertiger 2 November 2012 at 11:06 pm #

    I noticed an interesting letter to the BMJ on 11.10.12 …
    http://www.bmj.com/content/345/bmj.e6155/rr/607799
    … from Professor Peter Gotzsche of the Nordic Cochrane Centre,
    http://www.cochrane.dk/screening/index-en.htm
    … and the newly updated leaflet on ‘Screening for Breast Cancer with Mammography’.
    http://www.cochrane.dk/screening/mammography-leaflet.pdf
    At the end of the summary he writes’

    “It therefore no longer seems reasonable to attend for breast cancer screening. In fact, by avoiding going to screening, a woman will lower her risk of getting a breast cancer diagnosis. However, despite this, some women might still wish to go to screening.”

  11. Susan 3 November 2012 at 2:24 am #

    I have to come down on the “more harm than good” side.
    Several years ago, my new OB/GYN doctor sent me for a mammogram. Because of a strong family history of breast cancer, she elected to send me to the diagnostic mammogram department rather than the screening department. Of course, they found evidence of calcifications and called me back. By the time I was done with that place a couple of years later, I’d undergone two stereotactic biopsies, an open biopsy, and extra mammograms with additional films every time to “cone in” on the questionable areas. Along with all of that came the stress and worry. In the end, I was left with a diagnosis of “atypical lobular hyperplasia” — not cancer, and no guarantee that it would progress to cancer. I was encouraged to take Tamoxifen to prevent cancer, but ultimately declined. I was left with a scar and one visibly smaller breast due to the open biopsy.
    Is it any wonder that I didn’t have another mammogram for six years until my current doctor insisted. And even though he orders a mammogram every year, I don’t feel bad about skipping it every other year. With this new review, I may even push it to every 5 years.

  12. Kirsteen 3 November 2012 at 1:19 pm #

    @ Margaret, Thank you very much for the chart. I’ll print it out and take it to my surgeon when I go. I’m trying to push for ultrasound instead. My oncologist reckons it’s not as good but would be happy to let me have it but, at the end of the day, it’s the surgeon who has the final say.

  13. Dr John Briffa 3 November 2012 at 1:41 pm #

    Kirsteen

    it’s the surgeon who has the final say.

    Actually, you could have the opinion that it’s you who has the final say.

  14. Fiona 3 November 2012 at 4:34 pm #

    Just a word to say that, if you’re a 32A cup size and very slim, a mammogram is very uncomfortable, albeit only for a few minutes.

  15. Ginny 3 November 2012 at 8:13 pm #

    I agree with Dr. Briffa on the final say. I’ve let my doctors know I will have the final say on what happens to my body. I’m the one who has to live with it, or die with it.

  16. Kirsteen 3 November 2012 at 10:14 pm #

    “Actually, you could have the opinion that it’s you who has the final say.”

    Sorry, I should have been clearer. I have the final say as to whether I have a mammogram or not and I’m heavily, heavily leaning towards ‘not’ but the surgeon has the final say whether I can have an ultrasound instead or just do without.

  17. john barr 4 November 2012 at 12:34 am #

    Kirsteen
    Why should your surgeon have the final say on whether you have an ultrasound or not?
    As a GP in Australia, I can order an ultrasound for my patients if that is their wish. The surgeon’s opinion doesn’t matter. You will have the information which is available from an ultrasound, whether or not it is as useful as that from a mammogram, a now obviously debatable point.
    The patients can then make up their own minds on whether to have a mammogram or not, just as it is their right to decide on whether to proceed with any treatment or not. My job is to provide all the available information, and to help the patient navigate the murky waters of vested interests.

  18. Kirsteen 4 November 2012 at 2:48 pm #

    @John. That’s interesting. I’ve no idea why it works that way here in the UK. I saw the surgeon after the op, 3 months after, 6 months after and will now have yearly checkups for 5 years. I will automatically be called for a mammogram 4 weeks before each visit so she can discuss the results with me. I’ve just finished my year’s course of Herceptin, so have seen my oncologist for the final time. I voiced my reservations and preferences with her and she was quite agreeable but it’s the surgeon who’s in charge of my after care so apparently it’s up to her whether I’m offered an alternative or not. We agreed I’d cancel the appointment for the mammogram when I get it, and speak to the surgeon when I see her. It’s then up to her what she’s prepared to do. Meanwhile my oncologist will write and let her know how I feel about it. I’m heavily leaning towards saying ‘no’ whether offered an alternative or not as I feel, that due to previous CT scans, bone scans etc. I’ve had more than my fair share.

  19. helen 5 November 2012 at 1:05 am #

    Kirsteen I think a lot of what surgeons etc say is to frighten the patient into doing what they are told ……..ulitmately it is you who decides only you are responsible for your life regardless of what a doctor or specialist says ………..it is still only their opinion and they are not the ones who have to go through the proceedures……indeed most cancer specialists wouldnt’ have the treatment they give their patients so what does that tell you!! also does the treatment do more harm than the cancer??? ………..and fear is not a good place to be in when making huge descisions about your life.

  20. Liz 5 November 2012 at 4:52 pm #

    Cancer Research UK has reported the statistics that for every 1,000 women screened for 20 years, there are 5 extra lives saved at the expense of 17 women being diagnosed and treated for a cancer that would never have caused them any problem. Their figures report that well under 1 woman in 1000 would get a cancer caused by radiation. They say “You can’t know whether you will benefit from screening or end up having treatment that you might never have needed. If you choose to be screened, you are accepting the chance of having your life extended, but also risking being overdiagnosed and having at least a lumpectomy or mastectomy, and possibly other cancer treatment. If you choose not to have screening, you run a slightly higher risk of dying because a breast cancer wasn’t found early enough.” On balance, taking all the evidence into account, Cancer Research UK recommends that women go for breast screening when invited.”
    On balance, taking all the evidence into account, Cancer Research UK recommends that women go for breast screening when invited.”
    Here are their figures:-
    “After 20 years, out of 1,000 women who have screening, 75 will be diagnosed with breast cancer and have treatment. Out of these 75 women
    16 will die from breast cancer
    59 will be successfully treated and survive their breast cancer
    Whereas, after 20 years, amongst 1,000 women who have not had screening, 58 will be diagnosed with breast cancer. Of these 58 women
    21 will die from breast cancer
    37 will be successfully treated and survive their breast cancer

    It also says that “For every 10,000 women who have regular 3 yearly screening between the ages of 47 and 73, experts estimate that there will be between 3 and 6 extra breast cancers caused by radiation.

  21. Helen (another one!) 6 November 2012 at 12:42 am #

    I have visits to a hospital every couple of years to check progress of a non-cancerous breast condition. I resisted a mammogram on every visit – opting for ultrasound instead – until the last time, when the consultant expressed concern about the number of cysts I had at that time. The mammogram was performed carelessly and was a brutal experience. The cysts burst. I will never agree to a mammogram again. If there any serious suspicions in future, I will have to raise the money for thermography instead, even though the nearest clinic is several hours’ drive away.

  22. Cybertiger 6 November 2012 at 10:55 pm #

    Today, in the BMJ, James Penston, a Consultant Physician from Scunthorpe, delivered some cogent words about the value of breast screening …

    http://www.bmj.com/content/345/bmj.e7330/rr/613012

    … and the con of statistics-based evidence in medicine.

  23. Sue 1 December 2012 at 4:52 am #

    I concur with the person who said that they prefer to minimize their risk of developing cancer with nutrition. Mammography has never sounded like something I have wanted done to my body and as cancer is not a deficiency of toxic medications or radiation, I prefer to fight it with healthy food, exercise, positive thinking, detox and a great nights’ sleep (read “get checked for sleep apnea if you don’t experience restful sleep” as it is a huge contributor to disease including cancer)

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