How the UK Cancer Empire killed the debate on mammography screening

And how The Lancet starred as the establishment’s useful idiot

The history of mammography screening is a dire example that those who excel in dishonest research often win scientific debates in healthcare.^1-3

I started a debate in 2000⁴ that lasted 12 years until The Lancet killed it by publishing a flawed review⁵ and by providing seriously misleading comments to the public.⁶

Our first systematic review of the mammography screening trials appeared in The Lancet in 2000,⁴ and it created a media storm. We talked to radio and TV stations from all over the world explaining what we had found, which was shocking news, also for ourselves.¹

We documented that the randomisation process had failed to create similar groups in six of the eight trials of mammographic screening and that the number of randomised women was inconsistently reported in four of them.⁴

The two trials with adequate randomisation, from Canada and Malmö, found no effect of screening on mortality from breast cancer, not even a tendency towards an effect. By contrast, the effect of the six trials with inadequate randomisation was highly significant, and there was no overlap of the confidence intervals for the two effect estimates. This was a strong warning signal that raised serious doubts about the validity of these six trials.

We concluded that those who believe that the five Swedish trials – which had been highly influential - are unbiased have to accept from the data that screening for breast cancer with mammography causes more deaths than it saves. For every 1000 women screened throughout 12 years, one breast-cancer death is avoided but the total number of deaths is increased by six. Those who believe that the Swedish trials, apart from the Malmö trial, are biased have to accept that there is no reliable evidence that screening decreases breast-cancer mortality.

Our findings were very important, but throughout the next 25 years, numerous systematic reviews were published that wilfully ignored that four of the five Swedish trials are unreliable and included them in the summary estimate.

In 2001, we published the most detailed systematic review ever carried out, also in The Lancet.⁷ It confirmed and strengthened our findings and demonstrated that breast-cancer mortality is a biased outcome measure that favours screening, and that screening leads to more aggressive treatment, including more mastectomies. These findings would also be consistently ignored the next 25 years because they punctured totally the idea that mammography screening is useful and does more good than harm.

When a peer reviewer asked us what we meant by saying that we had read forty centimetres of literature, we took a photo of our documentation:

Ole Olsen, our secretary Tine Bjulf and Peter C Gøtzsche

No one but Ole and me has ever read all this, which included documents in Swedish.

Against fierce opposition and outright censorship, I succeeded publishing numerous critical research papers in the BMJ and other leading journals³ and two books.^1,2 They confirmed that screening:

· doesn’t save lives

· leads to substantial overdiagnosis that kills some healthy women

· leads to more surgery including more mastectomies

· is sold to the public by systematic disinformation.

A “Yes, Minister” report in The Lancet killed the debate

The heated debate about breast screening was killed in 2012 by a politically expedient but seriously flawed review in The Lancet,⁵ which was a ”Yes, Minister” whitewash.^1,8 It came out nine months after my book had documented in great detail how unreliable most of the randomised trials are.¹

The National Cancer Director in England and the Chief Executive Officer of Cancer Research UK had asked Professor Sir Michael Marmot to assemble and chair an independent panel to review the evidence for the benefits and harms of breast screening.⁵

I was invited to London to give oral testimony in February 2012, which was a weird experience because I had documented that several of the other invitees,⁹ including Dame Valerie Beral, Stephen Duffy, Harry de Koning, Lennarth Nyström, Julietta Patnick and Sir Nick Wald, had been scientifically dishonest.^1,2 I don’t want to meet with such people. Moreover, the panel members ignored totally my warnings - also when I submitted written comments after the meeting - that most of the trials were unreliable and that breast cancer mortality is a biased outcome.

The emperor was naked, but the Cancer Screening Empire succeeded burying the criticism of screening for good.²

We explained what was wrong with the Marmot report in a letter in The Lancet.⁸ The panel did not think that adjudication of the cause of death was a problem even though we had documented at length that it is a huge problem, which inevitably biases the trials in favour of screening even when blinded endpoint committees have been used.⁷

It was scientific misconduct to ignore this. The panel also opined that all-cause mortality is not an appropriate outcome because the trials did not have sufficient power for this. Whether an outcome is appropriate or not has nothing to do with power. And there was enough power. We noted that screening did not reduce total mortality or mortality from cancer, including breast cancer, and that some of the healthy overdiagnosed women will die from their treatment, e.g. radiotherapy increases deaths from heart disease by 27%.⁸

The panel didn’t publish any information on all-cause mortality or all-cancer mortality.

The panel referred to the data from our Cochrane review¹⁰ but used the erroneous estimate of a 20% reduction in breast cancer mortality, which was the average effect of all the trials that the Cochrane Breast Cancer Group had forced us to include despite our protests.^1,2 The panel also ignored that we wrote in the abstract that the trials with adequate randomisation had not shown a significant reduction in breast cancer mortality.

There were other serious errors. Contrary to the opinion of the panel, the important advances in treatment that had occurred since the trials were done had reduced the effect of screening substantially. We also noted that increased breast cancer awareness had reduced the effect.

The panel extrapolated the old data far beyond the data range, which is impermissible. They assumed that the 20% effect would exist undiminished up to age 79 years, ten years after screening stopped, which is unreasonable, and concluded that screening prevents about 1300 breast cancer deaths every year in the UK.

This was just too politically expedient. As they say in episode four of BBC’s “Yes, Minister” series: “The Prime Minister doesn’t want the truth, he wants something he can tell Parliament.” The 1300 lives saved are very close to the claim from 2008 by the UK Breast Screening Programme of 1400 lives saved, which assumed, however, that the effect was 35%, not 20%,¹¹ and its claim from 2002 of 1250 women saved.^2,12,13

Such manoeuvres are called torture your data till they confess.¹⁴

The Marmot panel’s estimate of 19% overdiagnosis was also misleading. We found 31% overdiagnosis in the two adequately randomised trials;^7,10 33% in Denmark,¹⁵ which has an ideal control group because 80% of the country was not screened for 17 years; and 52% in a systematic review of countries with organised screening programmes.¹⁶

We ended our Lancet letter with a question:⁸ “Is it acceptable that a public health initiative each year converts thousands of healthy women into cancer patients unnecessarily, which is fatal for some of them?”

The egregiously false messages to the public

The panel was fully aware of our results but ignored them, as they were inconvenient for the fairy tale it was expected to produce under the guise of an “independent” assessment.

In its press release, The Lancet mentioned that just over 1% of women aged 50-52 years will have an overdiagnosed cancer in the next 20 years.⁶ This is obscenely misleading. In 2009, we reported an overdiagnosis in the UK of 57%.¹⁶

The press release quoted Professor Marmot for saying that screening prevented one breast cancer death for every 235 women invited to screening.⁶ However, a flawed meta-analysis of the Swedish trials had reported a 29% reduction in breast cancer mortality after ten years,¹⁷ corresponding to one woman out of 1000 avoiding dying from breast cancer. Thus, Marmot’s estimate was four times more positive than an estimate that was already too positive.

The press release noted that, “For each woman, the choice is clear ... Clear communication of these harms and benefits to women is essential, and the core of how a modern health system should function.” This was hypocritical. The Lancet had just misinformed women in the extreme!

Breast surgeon Michael Baum set up the first breast screening centre in the UK in 1988 but resigned from the programme committee in 1997 when it refused to provide honest information to the invited women.¹⁸ The committee was concerned that such information would deter women from attending and that the target of more than 70% acceptance, on which the programme was predicated, would be missed.

Baum noted that “As a surgeon I have a legal and ethical commitment to describe to my patients the harms and the benefits of my interventions, but a double standard clearly exists among the screening community, who seem to be in denial.”

In his testimony to the panel, Baum said that “Those who are responsible for mammography screening don’t care the least that the way they sell it is blatantly and indisputably unethical.”¹ Baum also informed the organisers at Cancer Research UK (CRUK) that he had published a letter in The Times expressing his concerns on the absence of any information on all-cause mortality:

“To say that the trials were inadequately powered for this end point is a pathetic excuse. In the ProtecT trial of PSA screening for prostate cancer, cause specific and all-cause mortality are equal primary end points.”

Baum asked whose idea it was “to parade a group of women whose ‘lives had been saved’ by screening at the press conference? You should know of course that it is impossible to identify such women ... If the CRUK aren’t aware of this then they know nothing about screening and if they are aware then they are guilty of corporate scientific misconduct. Before I lodge a formal complaint, which of these two categories does the CRUK fit into?”

Baum cannot remember if he ever got a reply. I have no doubt that he would have remembered if CRUK replied.

An anonymous Lancet editorial,¹⁹ most likely written or approved by Editor-in-Chief Richard Horton, talked about closing a chapter; that the review “should begin to lay the benefits versus harm controversy to rest;” that “The Panel also considered how women feel about the available evidence: many women believe the balance of benefits to risks is worthwhile” (they cannot know this, as they have not been honestly informed); and that “Women need to have full and complete access to this latest evidence in order to make an informed choice about breast cancer screening” (which is impossible, given the Lancet report is so flawed).

The editorial contained no less than three errors in one sentence: “The Panel’s report, the latest and best available systematic review, shows that the UK breast-screening programme extends lives and that, overall, the benefits outweigh the harms.”

The best available systematic review was our review, which The Lancet published in 2001.⁷ The second best was our updated Cochrane review from 2011.¹⁰ Furthermore, the Marmot review was not even a systematic review, which a more comprehensive report published a year later acknowledged: “This is a rigorous review of the evidence by an independent panel; it is not a formal systematic review.”⁹

It is wrong to claim that breast screening extends lives, as total mortality is unaffected by it. I added more deaths in 2023;²⁰ the risk ratio for all-cause mortality was 1.01; 95% confidence interval 0.99 to 1.04. It is therefore also wrong to claim that the benefits – of which there are none - outweigh the harms, which, moreover, is a value judgment, not a scientific conclusion.

Richard Horton was on the advisory board for my Nordic Cochrane Centre, and he asked me to remove him, arguing that my criticism of the Marmot report “is damaging to women’s health and deleterious to the reputation of the Cochrane Collaboration. I don’t wish to be publicly associated with your view by being on your board.”²

It was my scientific and ethical duty to provide relevant criticism in The Lancet,⁸ and I fail to see how this can be damaging to women’s health and deleterious to the reputation of the Cochrane Collaboration. In fact, it is the opposite of what Horton claimed, which I have called the “You are killing my patients” argument.¹

When I informed my closest colleagues about this, Michael Baum replied: “I’m sick of people telling me it’s time to move on! Such a cliché. This isn’t marriage guidance counselling. To move on means learning from the mistakes of the past, not burying them.”

My co-author on the current version of the Cochrane review,²¹ Karsten Juhl Jørgensen, wrote to Baum and me that, “Richard Horton appears to think that if Peter stops criticising breast screening, we will have ‘world peace.’ That would perhaps be the case if the opposition against breast screening was indeed an international conspiracy orchestrated by the Nordic Cochrane Centre. But this process is not in the hands of Peter - it is a wave of new research by various independent research groups that have in common the realisation that breast screening has been oversold ... a consensus report that does not duly recognise the new evidence will obviously not end the debate.”

Unfortunately, Karsten was wrong. Horton, who had been so helpful 11 years earlier when Cochrane refused to publish the harms of screening, which he criticised in a scathing editorial that was very harmful for Cochrane’s reputation,²² now betted on the wrong horse, in no uncertain terms, and he killed the much-needed debate, which journal editors should not do.

Horton left a lot of bitterness and disappointment behind among people whose capacity for logical thinking was intact, and it is still around today.

I was devastated. I had devoted so much time for 15 years to get the truth out about mammography screening but I now realised it was impossible to win the battle because people who did not want the truth to come out were too powerful. Mammography screening is one of many interventions in healthcare that only survives because the public is being lied to.³

In 2014, I met with one of the authors of the Marmot report, Douglas Altman, ironically at the Preventing Overdiagnosis conference in Oxford. I asked him why he accepted to coauthor a report that was so flawed, and he admitted he wasn’t proud of it. Doug died of colon cancer in 2018. He was a close friend and one of the world’s finest biostatisticians. I have published more papers with him, over 50, than with anyone else, and his intellectual sharpness was legendary. He agreed with my major criticisms of the Marmot report, above all with the lumping of reliable with unreliable studies.

What this illustrates is very depressing. Group think and group pressure may trump science, even for one of the most outstanding scientists in the world.

In 2015, I explained once again, in a freely accessible article, why mammography screening is harmful and should be abandoned.²³ In 2024, I published a freely available book bout the , great mammography screening hoax, with updated information on the pervasive scientific and ethical corruption in this area of healthcare.² And in 2026, I wrote about Cochrane’s editorial misconduct when it refused to let us update our review with more deaths, which was such a horrific example of censorship that I called my article, “Cochrane on a suicide mission.”²⁰

Misleading information on websites and in invitation leaflets persists

After we had documented in the BMJ that the information offered to women on websites and in invitations to screening was highly misleading all over the world,^24,25 we wrote a leaflet ourselves. It was so popular that volunteers translated it into Arabic, Chinese (both traditional and simplified), Danish, Dutch, Finnish, French, German, Icelandic, Italian, Korean, Norwegian, Polish, Portuguese, Russian, Spanish, and Swedish.

As our initiatives over the years had had no impact in the Machiavellian power circles, we published a criticism of the new UK leaflet in 2009 in the BMJ and included our own leaflet. The UK leaflet had the authoritative title, “Breast screening: the facts,” and we therefore called our paper, “Breast screening: the facts - or maybe not.”²⁶ BMJ’s editor-in-chief, Fiona Godlee, said it was one of her top 20 articles in the last 20 years.²⁷

When 23 people from the UK, the US, Canada, Australia and France published a letter in The Times calling for action,²⁸ the usual mantras from the screening advocates had little effect. Only two days later, an article in The Times announced that the National Health Service was tearing up its leaflet and writing a new one from scratch.²⁹

Today, women in the UK typically receive a letter with a pre-booked appointment for screening. This is unethical, as it puts pressure on them to participate, as if it were a national duty. The misinformation is less pronounced than in 2009 but it is still there. The women are told that screening can save lives from breast cancer and that finding cancers early means that the treatment may be simpler.³⁰ They are not told that screening does not save lives, or that treatment is not “simpler,” as screening increases mastectomies.

The information currently offered on the website of Cancer Research UK is highly misleading. It claims that “The current evidence suggests that breast screening reduces the number of deaths from breast cancer by about 1,300 a year in the UK” and that “A 2012 breast screening review found that screening leads to around 4,000 women overdiagnosed in the UK each year.”³¹

Both estimates come from the Marmot report.

Mammography screening is a holy cow. To the great detriment of the hundreds of millions of women who trust the official propaganda.

Tell your female friends that they are being defrauded by opinion leaders, the media, cancer charities, and boards of health^1,2 and that they are wise if they decide not to attend mammography screening.

References

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

2 Gøtzsche PC. Mammography screening: the great hoax. Copenhagen: Institute for Scientific Freedom; 2024 (freely available).

3 Gøtzsche PC. Whistleblower in healthcare (autobiography). Copenhagen: Institute for Scientific Freedom 2025 (freely available).

4 Gøtzsche PC, Olsen O. Is screening for breast cancer with mammography justifiable? Lancet 2000;355:129-34.

5 Independent UK Panel on Breast Cancer Screening. The benefits and harms of breast cancer screening: an independent review. Lancet 2012;380:1778-86.

6 Independent panel concludes that breast cancer screening reduces deaths, but overdiagnoses. Ecancer 2012;Oct 30.

7 Olsen O, Gøtzsche PC. Cochrane review on screening for breast cancer with mammography. Lancet 2001;358:1340-2 and Olsen O, Gøtzsche PC. Systematic review of screening for breast cancer with mammography. Lancet 2001;Oct 20.

8 Gøtzsche PC, Jørgensen KJ. The benefits and harms of breast cancer screening. Lancet 2013;381:799.

9 Marmot MG, Altman DG, Cameron DA, et al. The benefits and harms of breast cancer screening: an independent review. Br J Cancer 2013;108:2205-40.

10 Gøtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database Syst Rev 2011;1:CD001877.

11 Jørgensen KJ, Gøtzsche PC. Who evaluates public health programmes? A review of the NHS Breast Screening Programme. J R Soc Med 2010;103:14–20.

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

13 NHS Breast Screening Programme. Does Breast Screening Save Lives? (accessed 2 October 2002, no longer available).

14 Mills JL. Data torturing. N Engl J Med 1993;329:1196-9.

15 Jørgensen KJ, Zahl PH, Gøtzsche PC. Overdiagnosis in organised mammography screening in Denmark. A comparative study. BMC Womens Health 2009;9:36.

16 Jørgensen KJ, Gøtzsche PC. Overdiagnosis in publicly organised mammography screening programmes: systematic review of incidence trends. BMJ 2009;339:b2587.

17 Nyström L, Rutqvist LE, Wall S, et al. Breast cancer screening with mammography: overview of Swedish randomised trials. Lancet 1993;341:973-8.

18 Baum M. Ramifications of screening for breast cancer: consent for screening. BMJ 2006;332:728.

19 The breast cancer screening debate: closing a chapter? Lancet 2012;380:1714.

20 Gøtzsche PC. Cochrane on a suicide mission. Brownstone Journal 2025;June 20.

21 Gøtzsche PC, Jørgensen KJ. Screening for breast cancer with mammography. Cochrane Database Sys Rev 2013;6:CD001877.

22 Horton R. Screening mammography – an overview revisited. Lancet 2001;358:1284-5.

23 Gøtzsche PC. Mammography screening is harmful and should be abandoned. J R Soc Med 2015;108:341-5.

24 Jørgensen KJ, Gøtzsche PC. Presentation on websites of possible benefits and harms from screening for breast cancer: cross sectional study. BMJ 2004;328:148-51.

25 Jørgensen KJ, Gøtzsche PC. Content of invitations to publicly funded screening mammography. BMJ 2006;332:538-41.

26 Gøtzsche P, Hartling OJ, Nielsen M, Brodersen J, Jørgensen KJ. Breast screening: the facts – or maybe not. BMJ 2009;338:b86.

27 Godlee F. Content is king. BMJ 2015;351:h3720.

28 Baum M, Vaidya JS, Thornton H, et al. Breast cancer screening peril: negative consequences of the breast screening programme. The Times 2009;Feb 19.

29 Smyth C. NHS rips up breast cancer leaflet and starts all over again. The Times 2009;Feb 21.

30 Your guide to NHS breast screening. NHS England 2026;Feb 23.

31 Breast screening (mammography). Cancer Research UK 2026 (undated).