Did the American College of Radiology accuse the BMJ mammography authors of misconduct?

This week the BMJ published the latest results from the Canadian National Breast Screening Study (CNBSS). A brief summary of the CNBSS: Women were randomly assigned to annual mammography or breast exams and then the outcomes tracked. The results in the BMJ: mammography did not improve survival.

This is a very interesting study and when I first started working on this post I wanted to delve more into the science of this article and the growing body of literature that is shedding some doubt on the validity of mammography. Doing my due diligence I read the study several times, read the responses that have already appeared on the BMJ site, read some other studies, and read both the Canadian and the American College of Radiology responses. And that’s where I got stuck.

The Canadian radiologists basically said they agreed with the ACR who call the study “Incredibly flawed and misleading” (which IMO are fighting words, it’s a bit like saying your study is a piece of garbage and should be ignored). Of course this piqued my interest.

The ACR claim rests on these 3 points:

  • The mammography equipment is old/bad and this was confirmed by independent experts. The lead author, Anthony Miller has refuted this claim in interviews with several Canadian news outlets and an expert from Dartmouth (Dr. Gilbert Welch) calls this study the most meticulously conducted and reported randomized trial on screening mammography. The ACR cites a paper in a radiology journal from 1990 that they say evaluated the equipment and Dr. B. Kopans, a Professor of radiology from Harvard, says he personally reviewed the equipment and found it lacking. How do you deal with these kinds of claims? Maybe ask the radiologists who read the films? It is an important point.
  • Only 32% of cancers were detected by mammography in the study. This is the most interesting from a scientific standpoint and not a “he said/she said” argument. I wanted to write more on this until I saw the last point made by the ACR…
  • Where the ACR basically accuses the authors of misconduct. The ACR statement: “To be valid, randomized, controlled trials (RCT) must employ a system to ensure that the assignment of women to the screening group or the unscreened control group is random. Nothing can/should be known about participants until they have been assigned to one of these groups. The CNBSS violated these fundamental rules. Every woman first had a clinical breast examination by a trained nurse so that they knew which women had breast lumps, many of which were cancers, and which women had large lymph nodes in their armpits many of which indicated advanced cancer. Before assigning the women to be in the group offered screening or the control women, investigators knew who had large incurable cancers. This was a major violation of RCT protocol. It most likely resulted in the statistically significant excess of women with advanced breast cancers assigned to the screening arm compared to those assigned to the control arm. This guaranteed more deaths among the screened women than the control women. The five year survival from breast cancer among women ages 40–49 in Canada in the 1980s was only 75 percent, yet the control women in the CNBSS, who were supposed to reflect the Canadian population at the time, had a greater than 90 percent five year survival. This indicates that cancers may have been shifted from the control arm to the screening arm. Coupling the fundamentally corrupted allocation process…   (the italics are mine).

However, the exact wording from the BMJ article about the randomization is as follows:

“The examiners had no role in the randomisation that followed; this was performed by the study coordinators in each centre. Randomisation was individual and stratified by centre and five year age group. Irrespective of the findings on physical examination, women aged 40-49 were independently and blindly assigned randomly to receive mammography or no mammography.”

So the authors are saying their randomization was blinded and the ACR’s counter-claim is that is couldn’t have been. Both can’t be right. The ACR is either accusing the author of lying or saying he had rogue study nurses who didn’t follow protocol. The ACR does not provide any references to support this claim.

This last part of the ACR claim sounds a lot like school yard taunt, “You lied. How do I know? Because I said so.” It is the kind of claim one makes when one A) hasn’t thought it all through and is letting emotions rule, B) has an otherwise weak argument that needs to be bolstered, or C) you want to be over the top to get page clicks. This accusation actually leads me to evaluate the ACR’s other two claims with greater scrutiny.

I contacted both the Canadian and the American Colleges of Radiology for clarification. I specifically asked the ACR for hard data to back up this 3rd claim. The Canadians said they’d call (they haven’t) and the ACR replied as follows:

“Critiques of study design and execution are routinely done for all scientific studies and do not constitute accusations of fraud. However, the irregularities in this trial design and execution raise valid scientific concerns. It is not a matter of whether we, or anyone else, “believe” trial coordinators, but that this is science. The responsibility lies with the trial conductors to demonstrate the soundness of the randomization process. It is not a matter of others in the scientific community to simply “believe.” The trial design and the subsequent outlier results raise these valid questions which are clearly outlined in many peer-reviewed publications cited in our response and elsewhere. We stand behind the statement that this study should not be used to formulate breast cancer screening policy.”

For me this statement isn’t enough. If you are a national organization representing physicians you cannot continue to make claims about how subjects were randomized without proof. Saying the patients weren’t randomized appropriately isn’t a study design issue, it’s an ethical conduct issue because the authors say they did randomize blindly. The science goes both ways. In essence the ACR is saying, facts matter but we don’t have to provide any.

If the ACR is right and the equipment was faulty and the science doesn’t support a 32% breast cancer detection rate by mammography why bring up a completely unsubstantiated 3rd claim about a corrupted randomization process? The science should be enough, don’t you think?

It’s food for thought.


Right after I hit publish I received an e-mail from the ACR. The post has been amended to include that.

Join the Conversation


  1. I wonder what the fee for an American radiologist to read a mammogram might be? Probably many times one of my Canadian FP office consults ($25CAN), and probably all that we need to know to assess where the ACR is coming from. I’m saddened that my colleagues can be so unprofessional when money is at stake.

    As for the study itself, it isn’t really a surprise. We have known for very many years that death rates from breast cancer have not fallen in countries after introduction of mammography. This shows that it isn’t due to an increase in breast cancer rates being balanced by better detection.

    1. That was my immediate thought. The ACR and the Canadian college have a vested financial interest in mammography, and, if correct, this report threatens their members’ income.

      Further, I was unsurprised to read that there were 106 ‘residual tumours’ in the screened population, attributed to over-diagnosis. Mammography isn’t risk free.

    2. As an engineer I sometimes grapple with whether the work I get paid for has social value. Like could I have been sitting on a beach with a cocktail ah la pink umbrella all the good I’ve done all this time? Maybe yes. Then again no one is forcing the customers to buy any of the stuff I work on. And the end result doesn’t involve some six year old kid staring in horror at his entrails for the last few seconds of his existence. So I’m good.

      But I’d hate to be a radiologist specializing in mammograms and be told most of the work I’ve done was pointless. That’d hurt.

      1. Although diagnostic mammograms have a definite role and screening mammograms may be valid for high risk women. However, the data is looking more and more like screening mammography may be the Emperor’s New Clothes. So, if you only do screening mammos that might be tough pill to swallow.

    3. Most radiologists are salaried with some incentive pay for RVUs (relative value units earned). Screening mammography is not a money maker. Radiologists looking to make more money have no interest in screening mammography. Liability is high.. Practices offer it because its an expected service, not because its a cost center that generates big income. Radiologists who recommend screening mammography do so because they’ve read the data that shows it saves lives. Metaanalysis of the eight major randomized controlled trials, which include this poor quality Canadian study, confirms decreased breast cancer mortality in women screened.

      1. Without arguing about whether the Canadian study is “poor quality”, the overall body of rigorous studies suggests that decreased breast cancer mortality is, at best, relatively meager – like early aggressive treatment of prostate cancer, if you would’ve been screwed without it, there’s an 80% chance that you’ll still be screwed with it and only get to spend more years disabled, fearful and broke before dying. And the TOTAL mortality does not change at all. The value judgements of radiologists and oncologists say that one should have great fear of dying of naturally occurring breast cancer and no fear of dying of iatrogenic heart failure following overdiagnosis and overtreatment, but I’d rather die of the former than the latter simply because it would gall me so terribly to know, or strongly suspect, that I’d shelled out my life savings to have it inflicted on me. Talk about total mortality, not just BC, BC, BC.

        And maybe talk about quality of life too. Overdiagnosis with screening means that even though some “real” cancers are found at an earlier stage, there are more total mastectomies, which often cause lasting pain or disability, more radiation treatments, more use of hormonal drugs that may impair cognitive function or inflict other diseases. Will I gain or lose QALYs by screening?

    4. Lancelotgobbo – I am sorry, but there are numerous studies that show that when screening is introduced the death rate from breast cancer falls. Death rates are independent of finding more cancers.

      Tabar L, Vitak B, Tony HH, Yen MF, Duffy SW, Smith RA. Beyond randomized controlled trials: organized mammographic screening substantially reduces breast carcinoma mortality. Cancer 2001;91:1724-31

      Duffy SW, Tabar L, Chen H, Holmqvist M, Yen M, Abdsalah S, Epstein B, Frodis Ewa, Ljungberg E, Hedborg-Melander C, Sundbom A, Tholin M, Wiege M, Akerlund A, Wu H, Tung T, Chiu Y, Chiu Chen, Huang C, Smith RA, Rosen M, Stenbeck M, Holmberg L. The Impact of Organized Mammography Service Screening on Breast Carcinoma Mortality in Seven Swedish Counties. Cancer 2002;95:458-469.

      Otto SJ , Fracheboud J, Looman CWN, Broeders MJM, Boer R, Hendriks JNHCL, Verbeek ALM, de Koning HJ, and the National Evaluation Team for Breast Cancer Screening* Initiation of population-based mammography screening in Dutch municipalities and effect on breast-cancer mortality: a systematic review Lancet 2003;361:411-417.

      van Schoor G, Moss SM, Otten JD, Donders R, Paap E, den Heeten GJ, Holland R,
      Broeders MJ, Verbeek AL. Increasingly strong reduction in breast cancer mortality
      due to screening. Br J Cancer. 2011 Feb 22. [Epub ahead of print]

      Otto SJ, Fracheboud J, Verbeek ALM, Boer R, Reijerink-Verheij JCIY, Otten JDM,. Broeders MJM, de Koning HJ, and for the National Evaluation Team for Breast Cancer Screening. Mammography Screening and Risk of Breast Cancer Death: A Population-Based Case–Control Study. Cancer Epidemiol Biomarkers Prev. Published OnlineFirst December 6, 2011; doi: 10.1158/1055-9965.EPI-11-0476

      Swedish Organised Service Screening Evaluation Group. Reduction in breast cancer mortality from organized service screening with mammography: 1. Further confirmation with extended data. Cancer Epidemiol Biomarkers Prev. 2006;15:45-51.

      Hellquist BN, Duffy SW, Abdsaleh S, Björneld L, Bordás P, Tabár L, Viták B,
      Zackrisson S, Nyström L, Jonsson H. Effectiveness of population-based service
      screening with mammography for women ages 40 to 49 years: evaluation of the
      Swedish Mammography Screening in Young Women (SCRY) cohort. Cancer. 2010 Sep 29.

      Coldman A, Phillips N, Warren L, Kan L. Breast cancer mortality after
      screening mammography in British Columbia women. Int J Cancer. 2007 Mar

      Kopans DB. Beyond Randomized, Controlled Trials: Organized Mammographic Screening Substantially Reduces Breast Cancer Mortality. Cancer 2002;94: 580-581

      Hofvind S, Ursin G, Tretli S, Sebuødegård S, Møller B. Breast cancer mortality
      in participants of the Norwegian Breast Cancer Screening Program. Cancer. 2013
      May 29. doi: 10.1002/cncr.28174. [Epub ahead of print]

      Paap E, Holland R, den Heeten GJ, et al. A remarkable reduction of breast cancer deaths in screened versus unscreened women: a case-referent study. Cancer Causes Control 2010; 21: 1569-1573.

      Mandelblatt JS, Cronin KA, Bailey S, et.al. Effects of mammography screening under different screening schedules: model estimates of potential benefits and harms. Annals of Internal Medicine, 2009; 151: 738-747; see also http://cisnet.cancer.gov, last accessed 16 April 2011.

      Broeders M, Moss S, Nyström L, Njor S, Jonsson H, Paap E, Massat N, Duffy S,
      Lynge E, Paci E; EUROSCREEN Working Group. The impact of mammographic screening
      on breast cancer mortality in Europe: a review of observational studies. J Med
      Screen. 2012;19 Suppl 1:14-25. Review

      Coldman A, Phillips N, Wilson C, Decker K, Chiarelli AM, Brisson J, Zhang B,
      Payne J, Doyle G, Ahmad R. Pan-canadian study of mammography screening and
      mortality from breast cancer. J Natl Cancer Inst. 2014 Oct 1;106(11).

      I can’t figure out how to reply to Dr. Gunter, but there is clear evidence that there was an allocation imbalance in the Canadian Study and that the images were of poor quality.

      Kopans DB. NBSS: Opportunity to Compromise the Process. Letter to the Editor. Can Med Assoc J 1997;157:247.

      Boyd NF, Jong RA, Yaffe MJ, Tritchler D, Lockwood G, Zylak CJ. A Critical Appraisal of the Canadian National Breast Cancer Screening Study. Radiology 1993;189:661-663.

      Kopans DB, Feig SA. The Canadian National Breast Screening Study: A Critical Review. AJR 1993;161:755-760.

      Kopans DB, Halpern E, Hulka CA. Statistical Power in Breast Cancer Screening Trials and Mortality Reduction Among Women 40-49 with Particular Emphasis on The National Breast Screening Study of Canada. Cancer 1994;74:1196-1203.

      Tarone RE. The Excess of Patients with Advanced Breast Cancers in Young Women Screened with Mammography in the Canadian National Breast Screening Study. Cancer 1995;75:997-1003.

  2. The mammogram lobby is swift in invalidating anti-mammogram research as unsound but they keep quiet about their MANY seriously faulty studies in favor of the test. This indicates that one needs to review the larger picture on mammography. The evidence against mammography is large, irrefutable, and substantial (see “The Mammogram Myth” by Rolf Hefti). Likewise, the hype/propaganda in favor of mammography is strong, continuous, and deafening.

    If a woman (and many regular doctors) looks PAST the pro-mammogram claims of the medical establishment she will quickly see that women have been profoundly misguided about the real value of mammography, going on for a long time.

    Considering the increasing data against the general use of this test, the mammogram industry and their defenders, do what they’ve always done: either ignore or downplay the significance of this data or partly concede, in a face-saving manner, to the inconvenient facts by claiming now that the choice to have a mammogram is a “an individual patient decision,” as if these tactics of damage-control would change an iota on the true facts about the exceedingly harmful procedure.

  3. Interesting post, Dr. Gunter. Good points. We certainly need better screening methods that are more calibrated to individual risk. Two questions regarding that 75% vs. 90% difference in 5-year survival between controls and the population they represent. Is there disagreement as to the accuracy of this disparity? And if not, have the investigators offered an explanation for this difference? Harsh words by ACR aside, this disparity is a potential marker for some factor that could have affected the study outcome. The burden of offering a potential explanation for it should fall to the study authors, I think.

  4. I would like to take the discussion to a totally different place; i.e. breast screening and what needs to be done in order to deliver the promise it bears to women. My worst nightmare, and I’m sure I’m sharing it with many men and women, is that all these discussion about effectiveness (cost/effectiveness) of mammography based screening of breast cancer will lead to the bright idea of pulling the plug on the only official cancer screening program that is accepted world-wide.
    There is no doubt that early cancer detection is a worth-while target to fight for!
    Instead of crying about mammography failure, it’s time to find out what goes wrong and how breast screening pathways can be improved! And YES – based on imaging!

    If you ask from where I’m coming and what I have in mind, then read this;





    and there are many more tools and technology out there, including mammography and it’s derivatives that if used in a standardised and coherent way will deliver the breast screening promise. The way I see it, it’s all about improving on management!

  5. It seems feasible that the individuals (nurses) who assigned the women to either the control group or the screening mammography group may have thought they were doing women with lumps a favor by assigning them to the screening mammography group- feeling this new technology at the time would somehow benefit these women. How else would you explain 4 times as many advanced cancers in the mammography group? The point is that a properly designed study would randomize pts before a breast exam. This was a poor study design which allowed for bias to be introduced.

    1. Though there were significantly more advanced cancers found early in the screening group, the study authors say that the total number of women with lumps – which are usually benign! – was not significantly different between the two groups. The radiology lobby needs to address numbers rather than just making insinuations of fraud. Also, the study protocol included sending women with lumps detected by palpation, either present at the beginning or incident during the study, for DIAGNOSTIC mammography. If a woman had a giant 6-cm lump that felt like likely cancer, the coordinator did not have to put her into the screening arm to get her a screening mammogram as her only hope of diagnosis and treatment. She could get a diagnostic mammogram. So the charge makes no sense.

  6. I do not think the American College of Radiology directly accused us of misconduct, but Dr Kopans did so accuse me many years ago and after an investigation initiated by the National Cancer Institute of Canada I was completely exonerated of the charge. It is relevant that I was not alone in being accused of misconduct by Daniel Kopans around that time.

    See: Taubes G. How one radiologist turns up the heat. Science 1997;2275:1057.

  7. For those unaware, the recent commenter, Dr. Anthony Miller, was the chief investigator of the Canadian National Breast Screening Study. Should he revisit this site, I would much appreciate his response to the following questions:

    Is it possible that bias may have been introduced into the randomization process by performing a breast exam prior to randomization?

    How do you explain the fact that Denmark has one of the highest rates of breast cancer mortality in Europe whereas Sweden has one of the lowest? They have a similar populations ethnically, and identical treatment protocols. The only difference I see is that Sweden has had a high quality screening program for many year whereas Denmark has not.

    If I identify and diagnose a grade 3 invasive ductal carcinoma seen on a screening mammogram measuring less than 10mm in a patient found to have no axillary nodal involvement, I believe there is a high likelihood that I have prevented her death from breast cancer. Am I wrong? (This is rare, as only about 15% of breast cancers less than 10mm are grade 3. That’s why screening mammography works. The larger the lesion, the more likely it is to be a high grade “killer” breast cancer. Mammography finds cancers before they progress into high grade aggressive cancers.)

    If your daughter or granddaughter had a diagnostic mammogram because of a palpable lump and that lump turned out to be a simple cyst but the diagnostic mammogram (which essentially screens the rest of that breast) showed a non palpable mammographic abnormality suspicious for malignancy in a different part of the same breast, would you advise her not to undergo percutaneous biopsy? I’m making this personal because a physician has a personal responsibility to each patient they see to recommend what they believe is best for that individual patient. As a physician who has biopsied and performed breast exams on hundreds if not thousands of patients with breast cancer over the past 25 years, I frankly find the notion that a thorough breast exam can be a substitute for a high quality mammogram ridiculous. These are complimentary exams, both of value in the diagnosis of breast cancer at its earliest and most treatable stage.

    I greatly respect the the time and effort which you put into the CNBSS. Your study is an outlier. It should not be considered a personal offense to question why that is.

    1. Dr. Chough,

      I am responding to your comment that “mammography finds cancers before they progress into high grade aggressive cancers.” This is certainly true for the 60% of women screened who have predominantly fatty breast tissue. However, one of the primary – and virtually unreported – issues with mammography is that it is an ineffective screening tool for the 40% of women who have dense breast tissue (defined as having greater than 50% dense tissue in the breast). I have personally spoken to dozens of women (and received correspondence from hundreds more) who have had their invasive breast cancer missed by mammography for several years. They have typically only been diagnosed with late stage cancer after reporting symptoms to their physicians for years. Many of them had developed very large tumors (5 cm, 6, cm, 8 cm, 9 cm, 10 cm) that were missed by mammography even when palpable at those sizes. For these women, the mammogram was as ineffective as a diagnostic tool as it was as a screening tool. Their palpable cancers were typically “found” not by mammography but by ultrasound or by MRI, and only after they metastasized to the lymph nodes and other areas of the body. Studies conducted over the past decade indicate that mammography misses approximately 50% of invasive breast cancers in women with dense tissue.

      The fact that mammography (both film and digital) is less effective in dense tissue has been well documented in peer reviewed articles since the birth of breast cancer screening in the US (as far back as Wolff in the 70’s and more recently in articles by Kolb, Boyd, Kelly, Pisano, Weigert, and others). We know that more than 70% of invasive breast cancers occur in women with dense tissue. Yet, we recommend mammography for all women, even those 40% of women over the age of 40 who have dense breast tissue. These are the women who are more likely to develop invasive breast cancer, but for whom the mammogram is least effective. This is the root cause of the failure of mammography to reduce the rate of metastatic breast cancer in the US, and the reason that it has failed to have more of an impact on mortality. (Estimates of mortality reduction from screening mammograms range up to 30% reduction at the most optimistic).

      The ACR has led the fight against informing women about the ineffectiveness of mammography for women with dense tissue. They have also led the fight against individuals and independent organizations (as in the 2009 USPSTF breast cancer screening recommendations) which have attempted to present balanced information and recommendations to the public.

      I would simply caution that what most physicians and patients think that they know about mammography is not entirely accurate. As a result, we tend to perpetuate unrealistic expectations of this screening tool.

      1. In response to J Marron, many things are possible, but that does not mean that they occurred. An example of something often overlooked is that the randomized screening trial from which the greatest breast cancer mortality reduction was reported – the Swedish Two County Trial – was cluster randomized. That means that it is highly likely that there were differences in the prevalance of risk factors for breast cancer between the compared arms – but the authors of the reports of that trial can not discount this, as they have no data on breast cancer risk factors they can report.

        In contrast, in the Canadian National Breast Screening Study we knew whether a woman was found to have an abnormality on breast examination discovered by the examiners – all carefully trained in the intricacies of breast examination. So we can report the frequency of those abnormalities at the first screen, which we first did in 1992. For the women age 40-49 the numbers (and %) of those with such abnormalities were 3569 (14.1%) in the mammography arm and 3674 (14.6%) in the control arm, while the corresponding figures for the women age 50-59 were 2164 (11.0%) and 2207 (11.2%), respectively. Thus the bias that J Marron postulates did not occur in the Canadian National Breast Screening Study.

        Anthony Miller

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