Breast Cancer Screening

An independent review is under way

BMJ 2011; 343 doi: http://dx.doi.org/10.1136/bmj.d6843 (Published 25 October 2011)
Cite this as: BMJ 2011;343:d6843

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We have already expressed concerns about the scientific validity and ethics of the ‘age extension trial’ (1). The independent Marmot review of breast screening acknowledges that for every life saved from breast cancer, three women are over-treated; i.e. every year 4000 more women who attend breast screening in the UK will receive a diagnosis and endure treatment for cancer that would never have affected them in their lifetime. Current literature does not state this risk clearly.

The Panel also concluded that “The impact of breast screening outside the ages of 50-69 years is very uncertain.” (2) Whilst stating that it “supports the principle [our italics] of the ongoing trial in the UK for randomising women under age 50 and above age 70 to be invited for breast screening”, their conclusions do not sit with current practice nor the trial rationale.

The screening roll-out has already started on the basis of assumed benefit. GPs are being advised to encourage women over 70 to attend screening and women are being randomised without giving explicit consent. How can women give truly informed consent for research when they are not told the truth? We again call for a moratorium on this trial.

References

1. Blennerhassett M, Havercroft D. Pryke M, McCartney M, Bewley S, Broderson J.
Extending breast cancer screening beyond its limits without waiting for evidence. http://www.bmj.com/content/343/bmj.d6843?tab=responses (accessed 31 October 2012)

2. The Independent UK Panel on Breast Cancer Screening. The Benefits and Harms of Breast Cancer Screening. Independent Breast Screening Review. A report jointly commissioned by Cancer Research UK and the Department of Health (England). 2012;(Oct):70http://www.cancerresearchuk.org/prod_consump/groups/cr_common/@nre/@pol/documents/generalcontent/breast-screening-report.pdf (accessed 31 Oct 2012)

Competing interests: The views expressed are not those of the Yorkshire Cancer Network or their User Partnership Group. MB, MMcC, SB have contributed to a review of the present cancer screening information strategy being conducted by King’s Health Partners. MB and MMcC receive royalties from written books on cancer and medicalisation respectively. SB wrote an open letter calling for an independent review BMJ 2011;343:d6843. MB is a breast cancer patient.

Mitzi AJ Blennerhassett, medical writer

Daphne Havercroft, Member of the public/ patient advocate, Miriam Pryke, PhD student, Kings College, London Margaret McCartney, General Practitioner, Susan Bewley, Professor of Complex Obstetrics, Kings College London, John Brodersen MD, GP, PhD, Associate Research Professor.

Yorkshire Cancer Network user partnership group, Harrogate, North Yorkshire

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The Director of the NHS Cancer Screening Programmes has recently encouraged GPs to refer women over 70 for breast screening1. She appears convinced of the benefit despite the ongoing independent Marmot review of breast screening, and National Cancer Director Professor Sir Mike Richard’s surprise announcement2 in the BMJ that women over 70 presently receiving invitations for screening are actually part of a randomized controlled trial (RCT).3

The trial website states, “… to date there is limited evidence on the net benefit of extending (up or down) the age range for breast screening… This study proposes randomising the phasing-in of the age extension and collecting information on breast cancer incidence and mortality over the following 10 years... The age extension will proceed regardless of whether this study goes ahead or not, and therefore regardless of whether the phasing-in is randomised or not.” 3 The trial is billed as exploiting the government’s commitment to national roll-out but no equipoise is expressed about extending screening – a normal prerequisite before formulating RCT questions. The website claims, “This would provide unbiased evidence on the net effects of extending the age range for breast screening”. It would not: the outcome, breast cancer mortality, is inevitably biased in favour of screening4 and should be total mortality (or, second-best, total cancer mortality). The invitation leaflet women receive states, “Eventually all women in the new age groups will be included” and does not state explicitly that acceptance means trial participation5. The weblink provided6 does not lead directly to information on the RCT. It is unusual scientific process to have pre-judged results: the benefit of more screening is already assumed yet an opportunistic trial was established.

Our concerns are: a) The reasoning given for the trial is inadequate; b) Human experimentation usually requires protection via an explicit consent process with properly informed participants; c) Women are not given unbiased information about the benefits and harms of screening, let alone that they will be participating in research using ‘default’ implied consent; d) The un-subtle implication, “If breast cancer is found early, you are less likely to have a mastectomy”7 is that women who attend screening are less likely to undergo mastectomy. In truth, they have a 20% higher risk4. Other studies also show that more breasts are removed when there is screening than not4,8,9; e) The distorted information leaflet contrasts markedly with high quality research trial materials and consent processes10; f) The need to search the internet for information discriminates against women for whom this is difficult or impossible. Questions about the ethics of this trial posed since November 2011 [MB] have either been ignored or answered unsatisfactorily.

GPs see the harms of screening - particularly anxiety, false positives, over-diagnosis and excess mastectomy for DCIS - and need confidence in the credibility of clinical advice from the NHS Cancer Screening Programme. Advice to doctors and citizens must be fair and evidence-based. To maintain trust, we recommend: 1) An immediate pause to examine the RCT’s research validity and ethical nature; 2) Re-review of the protocol and ambiguous information leaflets; 3) Breast screening to be moved from the Cancer arm of the NHS into Screening where it belongs.
References

1. Madlen Davies. Interview with Professor Julietta Patnick. Pulse. 23 August 2012 http://www.pulsetoday.co.uk/newsarticle-content/-/article_display_list/1... 23/08/12 (accessed 24 Sept 2012)
2. Richards M. Observations. Breast Cancer Screening. An Independent Review is Under Way. Observations. Breast Cancer Screening. BMJ 2011;343:d6843
www.bmj.com/content/343/bmj.d6843
3. ISRCTN. Evaluating the age extension of the NHS Breast Screening Programme. Evaluating the net effects of extending the age range for breast screening in the NHS Breast Screening Programme in England from 50-70 years to 47-73 years.) ISRCTN. http://www.controlled-trials.com/ISRCTN33292440 (accessed 24 Sept 2012)
4. Gøtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database of Systematic Reviews 2009, Issue 4. Art. No.: CD001877. DOI: 10.1002/14651858.CD001877.pub3.
5. NHS Breast Screening Programme. Extending the screening age range http://www.cancerscreening.nhs.uk/breastscreen/rollout-age-extension-lea... (accessed 24 Sept 2012)
6. http://www.cancerscreening.nhs.uk/ Link given does not lead directly to trial information which can be found at http://www.cancerscreening.nhs.uk/breastscreen/research-age-extension-pi... or http://www.cancerscreening.nhs.uk/breastscreen/research-age-extension-fu... (accessed 24 Sept 2012)
7. NHS breast screening. Leaflet page 3 http://www.cancerscreening.nhs.uk/breastscreen/publications/nhsbsp.pdf
(accessed 24 Sept 2012)
8. Jørgensen KJ, Keen JD, Gøtzsche PC. Is mammographic screening justifiable considering its substantial overdiagnosis rate and minor effect on mortality? Radiology 2011;260:621-6.
9. Suhrke P, Mæhlen J, Schlichting E, et al. Effect of mammography screening on surgical treatment for breast cancer in Norway: comparative analysis of cancer registry data. BMJ 2011;343:d4692.
10. For example, UK prostate cancer screening trial, ProtecT. http://www.bris.ac.uk/social-community-medicine/projects/protect (accessed 24 Sept 2012)

Competing interests: The views expressed are not those of the Yorkshire Cancer Network or their User Partnership Group. MB, MMcC, SB have contributed to a review of the present cancer screening information strategy being conducted by King’s Health Partners. MB & MM receive royalties from books on cancer and medicalisation respectively. MB is a cancer patient.

Mitzi AJ Blennerhassett, medical writer

Daphne Havercroft, Member of the public/ patient advocate, Miriam Pryke, PhD student, Kings College, London, Margaret McCartney, General Practitioner, Susan Bewley, MD FRCOG Professor of Complex Obstetrics, Kings College London, John Brodersen MD, PhD, General Practitioner and Associate Research Professor.

Yorkshire Cancer Network User Partnership Group (lay volunteer), Harrogate, North Yorkshire

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Dr. Barbara Monsees and Dr. Deborah L. Monticciolo present a mindset typical of screening advocates. It rests on an outdated understanding of breast cancer and on outdated evidence. Thereby they demonstrate the relevance of the ongoing independent UK review of the recent evidence.1

It was the recognition that early breast cancer is often a systemic disease that led to the findings that radical surgery of the primary lesion does not lead to better survival whereas systemic treatment certainly does.2 Advancing the time of diagnosis of a primary lesion will not improve its prognosis if it has spread systemically before screen-detection is possible, and screening preferentially detects the slow-growing lesions with an already favourable prognosis (length bias).

Their claim that screening offers “early detection”1 is more of a mantra than a reality. Screening advances the time of diagnosis of a primary tumour very little compared to the lifetime of the tumour.3 In the old trials, the tumour diameter was only 5 mm smaller in the screened group than in the control group, and this difference was even an overestimate because of the many small overdiagnosed tumours in the screened group.3

Being stuck in an outdated mindset often leads to neglect of unwelcome research results. We now know with a great deal of certainty that breast screening does not lead to fewer large cancers at the time of detection.4,5,6 The rate of tumours over 20mm in diameter has not been reduced despite decades of intense breast screening.4,5 A recent comparison of screened and unscreened regions in Norway showed that screening has not reduced the occurrence of stage III or IV disease, but has led to massive overdiagnosis of invasive breast cancers.6

If screening doesn't reduce the rates of late stage disease, it cannot reduce breast cancer mortality. This fits only too well with studies comparing breast cancer mortality rates in screened and non-screened regions within the same country7,8, as well as comparisons between countries with and without screening.9 Women in the Western world have enjoyed large declines in breast cancer mortality, regardless of the presence of breast screening in their country, and women too young to be screened have enjoyed an even larger decline.10 We cannot rely on the findings in the randomised trials performed decades ago, as most of them are flawed, as systemic treatment is much better today, and as women attend a doctor much earlier if she has noted a change in her breast.

An unchanged amount of large tumours means that the massive increase in the number of early stage invasive breast cancers and in situ cases with screening have not prevented their progression to late stage disease. They represent overdiagnosed cases, not early detection, and there is compelling evidence that many of them would have “melted away” if not detected by screening.11,12

Worst of all, Monsees and Monticciolo have either not read or not understood the research on overdiagnosis they criticize. It is a false claim that, “The publications on overdiagnosis failed to take into account lead time gained by screening, prevalence cases as each new cohort of women begins screening, and the background increase in breast cancer incidence that has been independent of screening.”1 We and others who have estimated the level of overdiagnosis at 30-50% have indeed taken account of all these factors, and we encourage readers to check our publications for themselves, in this journal13 and elsewhere14.

Monsees and Monticciolo also misrepresent the level of overdiagnosis in the randomised trials. Collectively, the level of overdiagnosis in the trials was 30%15, but they cherry-pick a lower estimate of 10% from a single trial16, which has been shown to be diluted by 15 years of additional follow-up after screening ended17,18 and by the screening of the control group during the randomised phase of the trial. When corrected for this, there was 25% overdiagnosis in this trial.18

References
1. Monsees B, Monticciolo D. An open letter to Professor Sir Mike Richards and Dr. Harpal Kumar. BMJ Rapid Response 11 April 2012. http://www.bmj.com/content/343/bmj.d6843?tab=responses.
2. Baum M. Breast Beating. Kent: Anshan Ltd., 2010.
3. Gøtzsche PC, Jørgensen KJ, Zahl PH, Mæhlen J. Why mammography screening hasn’t lived up to expectations from the randomised trials. Cancer Causes Contr 2012; 23:15-21.
4. Autier P, Boniol M, Middleton R, Doré J-F, Héry C, Zheng T, et al. Advanced breast cancer incidence following population based mammographic screening. Ann Oncol 2011;22:1726-35.
5. Nederend J, Duijm LEM, Voogd AC, Groenewoud JH, Jansen FH, Louwman MWJ. Trends in incidence and detection of advanced breast cancer at biennial screening mammography in The Netherlands: a population based study. Breast Cancer Res 2012;14:R10. doi:10.1186/bcr3091.
6. Kalager M, Adami HO, Bretthauer M, Tamimi RM. Overdiagnosis of invasive breast cancer due to mammography screening: results from the Norwegian screening program. Ann Int Med 2012;156:491-9.
7. Jørgensen KJ, Zahl PH, Gøtzsche PC. Breast cancer mortality in organised mammography screening in Denmark. A comparative study. BMJ 2010;340:c1241.
8. Kalager M, Zelen M, Langmark F, Adami HO. Effect of screening mammography on breast-cancer mortality in Norway. N Engl J Med 2010;363:1203-10.
9. Autier P, Boniol M, Gavin A, Vatten LJ. Breast cancer mortality in neighbouring European countries with different levels of screening but similar access to treatment: trend analysis of WHO mortality database. BMJ 2011;343:d4411. doi: 10.1136/bmj.d4411.
10. Autier P, Boniol M, LaVecchia C, Vatten L, Gavin A, Héry C, et al. Disparities in breast cancer mortality trends between 30 European countries: retrospective trend analysis of WHO mortality database. BMJ 2010;341:c3620.
11. Zahl PH, Mæhlen J, Welch HG. The natural history of breast cancers detected by screening mammography. Arch Intern Med 2008;168:2311-6.
12. Zahl PH, Gøtzsche PC, Mæhlen J. Natural history of breast cancer detected in the Swedish mammography screening programme: a cohort study. Lancet Oncol 2011;12:1118-24.
13. Jørgensen KJ, Gøtzsche PC. Overdiagnosis in publicly organised mammography screening programmes: systematic review of incidence trends. BMJ 2009;339:b2587.
14. Jørgensen KJ, Zahl PH, Gøtzsche PC. Overdiagnosis in organised mammography screening in Denmark. A comparative study. BMC Women’s Health 2009;9:36.
15. Gøtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database Syst Rev 2009, Issue 4. Art. No.:CD001877.
16. Zackrisson S, Andersson I, Janzon L, Manjer J, Garne JP. Rate of overdiagnosis of breast cancer 15 years after end of Malmö mammographic screening trial: follow-up study. BMJ 2006;332:689-92.
17. Zahl PH, Mæhlen J. A confusing definition of overdiagnosis. BMJ 7 March 2006. http://www.bmj.com/content/332/7543/689?tab=responses.
18. Welch HG. How much overdiagnosis? BMJ 10. March 2012. http://www.bmj.com/content/332/7543/689?tab=responses.
19. Gøtzsche PC. Overdiagnosis in the Malmö screening trial was considerably underestimated. BMJ 16 March 2006. http://www.bmj.com/content/332/7543/689?tab=responses.

Competing interests: None declared

Karsten J Jørgensen, MD

Peter C Gøtzsche

The Nordic Cochrane Centre, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark

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13 April 2012

It is axiomatic that screening must be predicated on knowing the natural history of disease (1). If radiologists have not studied the natural history of mammographic detected abnormalities, undisturbed by biopsies that might provoke some impalpable lesions out of dormancy, then how could anyone know whether screen-detected lesions (or 'cancers') melt away or not (2)? As trauma is known to provoke changes in tumour growth and biology (3,4,5) and dormant lesions may be in a state of dynamic equilibrium with micrometastases (6), screeners' confidence in their tools and interpretive skills might be misplaced. Finally, why should we trust breast radiologists whose livelihood rests upon present-day screening paradigm beliefs when they cast aspersions on the credibility of members of the Cancer Director's independant review panel (2) whilst simultaneously denying their own competing interests?

1) Wilson JM, Jungner YG. Principles and practice of mass screening for disease. Bol Ofi cina Sanit Panam 1968;65:281–393

2) Monsees B, Monticciolo D. An open letter to Professor Sir Mike Richards and Dr Harpul Kumar. http://www.bmj.com/content/343/bmj.d6843?tab=responses

3) Retsky MW, Demicheli R, Hrushesky WJ, Baum M, Gukas ID. Dormancy and surgery-driven escape from dormancy help explain some clinical features of breast cancer. APMIS 2008;116(7-8):730-41

4) Stuelten CH, Barbul A, Busch JI, Sutton E, Katz R, Sato M, Wakefield LM, Roberts AB, Niederhuber JE. Acute wounds accelerate tumorigenesis by a T cell-dependent mechanism. Cancer Res 2008;68:7278-82

5) Demicheli R, Fornili M, Ambrogi F, Higgins K, Boyd JA, Biganzoli E, Kelsey CR. Recurrence dynamics for non-small-cell lung cancer: effect of surgery on the development of metastases. J Thorac Oncol 2012;7(4):723-30

6) Willis L, Alarcón T, Elia G, Jones JL, Wright NA, Tomlinson IP, Graham TA, Page KM. Breast cancer dormancy can be maintained by small numbers of micrometastases. Cancer Res 2010;70(11):4310-7

7) Bewley S. The NHS breast screening programme needs independent review. BMJ 2011; 343:d6894. doi: 10.1136/bmj.d6894.

Competing interests: I have declined screening mammography (7) and have no competing interests to declare

Susan Bewley, Professor of complex obstetrics

Kings College London, 10th floor St Thomas' Hospital, Westminster Bridge Rd, London SE1 7NH

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We certainly support objective reviews of the scientific evidence concerning
breast cancer screening. We understand that there is a review underway in the UK, and therefore, we hope to draw your attention to several important concerns. The most recent arguments by those seeking to limit access to mammography screening [1] center on exaggerated claims of "overdiagnosis" leading to "overtreatment". Unfortunately, we feel that the estimate of the magnitude of overdiagnosis is erroneously high due to a combination of factors.

The publications on overdiagnosis failed to take into account lead time gained by screening, prevalence cases as each new cohort of women begins screening, and the background increase in breast cancer incidence that has been independent of screening. It has been suggested that 30-50 percent of breast cancers found by mammography would "melt away" if left alone, yet there is no series documenting such disappearing cancers. The best, and perhaps the only way to accurately measure overdiagnosis is to compare cancers in the screened women to those in the control group in randomized, controlled trials. This has been done, and the high estimate is just under 10 percent [2] down to under 1 percent [3]. The overestimates of overdiagnosis were at the heart of the recent Canadian Task Force on Preventive Health Care's [4] suggestion that screening be limited to every three
years for women ages 50-74. We hope that the UK group is aware of the major methodological problems with these publications on overdiagnosis and is not similarly misled.

We are also concerned about potential biases among selected members of the review committee that might undermine a fair and balanced review. We ask you to reconsider the membership of the review committee, so that the process can be objective and its product based on the best scientific evidence. One of the members listed on the website, although highly qualified, is also an advisor to the "Nordic Cochrane Center" which has been the major source of publications on overdiagnosis. Similarly, another panel member, although also qualified, is from the Dartmouth Medical School, from which many of the arguments against screening have been made.

Many of the challenges to screening have been legitimate. The need for randomized, controlled trials was indisputable. However, since 1993, most of the arguments against screening have been manufactured, and are scientifically unsupportable (particularly with regard to not offering screening to women ages
40-49) [5]. Since it is now scientifically clear that screening beginning at the age of 40 reduces mortality from breast cancer, opponents have begun to argue against it by exaggerating the issues of "overdiagnosis" and "overtreatment". Importantly, these are not restricted to mammographically detected lesions.

Mammography is not perfect. It does not find all cancers and does not find all cancers early enough to result in a cure, but therapy is successful at saving lives when cancers are found early. The death rate from breast cancer has decreased due to screening. No universal cure is on the horizon, and, until one is found, early detection offers the best chance for curative therapy. It would be most
unfortunate to set back women's health by reducing their access to screening.

Barbara Monsees, MD
Chair, Breast Imaging Commission
American College of Radiology

Debra L. Monticciolo, MD President
Society of Breast Imaging

1. Gøtzsche PC. Time to stop mammography screening? CMAJ. 2011 Nov
22;183(17):1957-8.

2. Zackrisson S, Andersson I, Janzon L, Manjer J, Garne JP. Rate of
over-diagnosis of breast cancer 15 years after end of Malmo mammographic screening trial: follow-up study. BMJ. 2006;332:689-92

3. Duffy SW, Agbaje O, Tabar L, Vitak B, Bjurstam N, Björneld L, Myles JP, Warwick J.Overdiagnosis and overtreatment of breast cancer: estimates of overdiagnosis from two trials of mammographic screening for breast cancer. Breast Cancer Res. 2005;7:258-65.

4. The Canadian Task Force on Preventive Health Care. Recommendations on screening for breast cancer in average-risk women aged 40-74 years. CMAJ.
2011;183(17):1991-2001

5. Kopans DB. The 2009 US Preventive Services Task Force
(USPSTF) guidelines are not supported by science: the scientific support for mammography screening. Radiol Clin North Am. 2010 Sep; 48(5):843-57

Competing interests: None declared

Barbara Monsees, Breast Imaging Radiologist

Debra Monticciolo

Washington University, St. Louis, 510 S. Kingshighway Blvd, St. Louis, MO, 63122, USA

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In October 2011, Mike Richards, the national clinical director for cancer and end of life care, announced that an independent review of mammography screening was under way (1). He noted that a new process for developing written information for the public was being established, which will take account of current thinking on how to synthesise information on benefits and harms and how to present these so as to promote informed choice. He furthermore announced that the breast screening leaflet will be one of the first products to be revised through this new process.

The Nordic Cochrane Centre published its own screening leaflet in the BMJ in 2009, together with a detailed criticism of the UK screening leaflet (2). The UK leaflet was misleading and contained serious errors. For example, it implied that screening leads to fewer mastectomies, although it is clear from both the randomised trials and rigorous observational studies with a relevant control group that screening increases mastectomies (3-5), and it did not mention the major harms of screening, overdiagnosis and subsequent overtreatment.

A revised UK leaflet was published just before Christmas in 2010. This leaflet was also seriously misleading. For example, it says that one breast cancer death is prevented for every 400 women screened regularly over 10 years, which is wrong by a factor of five (3,6). It doesn't describe overdiagnosis either, in fact the text is so ambiguous that many people would interpret it as a chance of cure rather than overdiagnosis (6).

Official information to the public in other countries about mammography screening is similarly misleading as that offered in the UK (7). I believe this is the reason that volunteers have translated The Nordic Cochrane Centre's screening leaflet into 11 languages.

We have just published an updated our leaflet in English and Danish (see www.cochrane.dk) and will have it translated into the other languages, too. The summary of the leaflet has been changed substantially, as its last sentences now are:
"More recent studies suggest that mammography screening may no longer be effective in reducing the risk of dying from breast cancer.
Screening produces patients with breast cancer from among healthy women who would never have developed symptoms of breast cancer. Treatment of these healthy women increases their risk of dying, e.g. from heart disease and cancer.
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."

The UK Breast Screening Programme paid virtually no attention to the serious criticism it received of its two previous leaflets. I hope that the independent review committee will pay attention to our updated leaflet when it revises the UK leaflet, so that the UK leaflet may "promote informed choice", as Richards put it. After 24 years of breast screening in the UK, this is about time, isn't it?

1. Richards M. An independent review is under way. BMJ 2011;343:d6843.

2. Gøtzsche P, Hartling OJ, Nielsen M, Brodersen J, Jørgensen KJ. Breast screening: the facts - or maybe not. BMJ 2009;338:446-8.

3. Gøtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database Syst Rev 2009;4:CD001877.

4. Jørgensen KJ, Keen JD, Gøtzsche PC. Is mammographic screening justifiable considering its substantial overdiagnosis rate and minor effect on mortality? Radiology 2011;260:621-7.

5. Suhrke P, Maehlen J, Schlichting E, Jørgensen KJ, Gøtzsche PC, Zahl PH. Effect of mammography screening on surgical treatment for breast cancer in Norway: comparative analysis of cancer registry data. BMJ 2011;343:d4692.

6. Gøtzsche PC, Jørgensen KJ. The Breast Screening Programme and misinforming the public. J R Soc Med 2011;104:361-9.

7. Gøtzsche PC. Mammography screening: truth, lies and controversy. London: Radcliffe Publishing; 2012.

Competing interests: None declared

Peter C Gøtzsche, Professor

Nordic Cochrane Centre, Rigshospitalet, Copenhagen, Denmark

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Professional indecision over breast screening does not make rational decision-making impossible for clients. What is impossible right now is getting answers to whether if at all screening prevents deaths and at what cost in unnecessary treatments.

That does not entail that clients cannot make a sensible decision about screening. From their perspective, in view of uncertainty, it would seem eminently reasonable not to attend. Indeed it would seem irrational to attend - a triumph of hope over lack of evidence - a leap of faith.

It would be that, if women attending knew about the dispute. The current screening invitations make bold claims without hinting that qualified professionals disagree. Women have never heard of the Nordic Cochrane Centre who gave the facts in 2000 (1), facts the NHSBSP has kept from them. So women are not leaping blindly. They are rationally following the advice of an organization they trust, which has the authority of expertise and government sanction. Those aware of the controversy cannot bring themselves to draw the logical conclusion: that the NHSBSP has seduced many thousands of women into grievous bodily and mental harm. It is so shocking to discover that a respected organization taking responsibility for people's lives has so distorted the facts for so long that women think there must be another explanation. Premise: the NHS just wouldn't do that. Conclusion: the others must be wrong. Valid argument. False premise. The NHS are doing just that.

The NHS scares women into attendance by suggesting they are otherwise at greater risk of breast cancer death (2,3). Controversy indicates this cannot be confidently accepted. Women's attitude to breast cancer should be the same as to other illnesses. They are many times more likely to get something else, for which screening is not done, yet they are not unduly anxious about that. They may get breast cancer, or something else, and if or when they do, there is treatment, it may work, that's life. Screening is not prevention and if today one has no signs of illness, is it unreasonable to be thankful for one's blessings? We should not be so psychologically dependent on institutional healthcare that fallible human beings can undermine our confidence in our own health, strength and judgment while they last.

Strictly speaking, it is impossible to get answers to those questions from the NHS. We have reliable answers from the Nordic Cochrane Centre, whose raison d'etre, aware that factors can distort opinion, is to scrutinize available evidence and provide the best possible information on which to base decisions, and from Klim McPherson who surveyed the evidence on screening for the BMJ and drew similar conclusions (4). But the NHS doesn't like their answers and wants Mr Richards to find answers they like.

Pending his report, will he ensure the NHSBSP now issues an explanation of what they should always have explained: that screening carries serious risks while the purported benefits are unproven? Women will be quite able to make a rational decision on that basis.

References

1) Is screening for breast cancer with mammography justifiable? Peter C Gotzsche, Ole Olsen. The Lancet Vol 355 January 8, 2000.

2) NHS Breast Screening Leaflet http://www.cancerscreening.nhs.uk/breastscreen/publications/nhsbsp.pdf

3) Health Trust letter and disclaimer sent to women requesting cessation of unsolicited appointments.

4) Screening for breast cancer--balancing the debate. Klim McPherson. BMJ 2010; 340:c3106.

Competing interests: Diagnosed following screening

Miriam Pryke, PhD student

King's College London

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Whilst the controversy continues and we await the findings from an independent group of reviewers (with all the attendant difficulties already elucidated by previous rapid reponse authors regarding the selection of reviewers and then acceptance of their recommendations), what are the women receiving their screening appointments in the meantime meant to do ? It seems difficult now to find an unbiassed form of words that permits any woman to make sense of the wisdom or otherwise of attendance unless she is manifestly at high risk. The mantra that 'finding things early' is essentially a good thing is so inculcated into our collective psyche that even-handed appraisal of the data and rational decision-making is virtually impossible. I've worked within the field of breast cancer research for more than 27 years, have read all the opinions of epidemiologists and others, and scrutinised the latest publications, but even I remain uncertain about the value of screening mammography. I feel simultaneously silly for attending but scared not to do so.

Can I also point out the absolute neccessity for funding and support of trials that are attempting to establish something informative about the natural history of low grade DCIS, the diagnosis that seems to form the bulk of the women who may be overtreated.

Competing interests: None declared

Lesley J Fallowfield, Psycho-oncologist

Brighton & Sussex Medical School

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Sir,

Professor Richards has presided over the breast cancer screening programme for the past 12 years. During this time, participants have been persistently misled by the information provided to them. [1-3] Five years ago, he was responsible for the introduction of the bowel cancer screening programme in England. Once again, the information sent to participants has been misleading in terms of the benefits and the adverse effects of screening. [4]

Professor Richards now proposes an independent review of breast cancer screening. [5] We can have little confidence in this process. The data from statistics-based research leave much latitude for interpretation and may easily be twisted and distorted in order to support a particular point of view [4] - in other words, they are ideal for the zealots whose attitude towards screening is more of a religion than a science. Given the very small treatment effects in absolute terms, the temptation to manipulate the data in order to support claims of benefit will continue to be strong.

Nobody can doubt the need for a review of cancer screening. Yet this should not be confined to breast cancer. The bowel cancer screening programme also requires close scrutiny. But if such a review is to be taken seriously, then all of those who have been involved in the deceptions associated with breast and bowel cancer screening should be excluded. As the cancer tsar, Professor Richards is no exception.

James Penston

e-mail: james.penston@nhs.net

References

1. Baum M. Ramifications of screening for breast cancer: Consent for screening. BMJ 2006;332;728.

2. Gotzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database Syst Rev 2006;(4);CD001877.

3. Gotzsche PC, Jorgensen KJ. The Breast Cancer Screening Programme and misinforming the public. J R Soc Med 2011;104;361-369.

4. Penston J. Stats.con - How we've been fooled by statistics-based research in medicine. The London Press. London, November 2010

5. Richards M. An independent review is under way. BMJ 2011;343;d6843.

Competing interests: None declared

James Penston, Consultant Physician/Gastroenterologist

Scunthorpe General Hospital, Scunthorpe, North Lincolnshire DN15 7BH

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Well written (Chris Hiley). I have experience of a breast cancer charity's misguided, blinkered and dogmatic approach. As a breast cancer advocate team member I attended their annual Westminster gathering last year. I was surprised when no-one mentioned the latest evidence and controversy over screening and shocked that I was not allowed to pose a question on the subject to visiting Prof Mike Richards.

Meanwhile, participants were regimented and shunted to meet with MPs to lobby for yet more screening. Emperor's New Clothes? I was definitely the fly in their soup. I resigned.

Competing interests: None declared

Mitzi AJ Blennerhassett, medical writer

Yorkshire Cancer Network user partnership group

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