Mammograms – Time to pull the plug?

May 12, 2014 | By | 3 Replies More

Researcher say mammograms don’t reduce deaths from breast cancer

By Alan Cassels  

I was about to call it a day when an email arrived with the following in the subject line: “The Best Health Advice You’ll Get Today.” That caught my attention.


Should routine mammograms for healthy women be stopped?

I was curious. And I’m a sucker for free health advice. I’ve got more than just a passing interest in health advice, seeing as I spend much of my working hours examining the quality of evidence that underlies what people say about drugs, screening and other kinds of health treatments. So when someone wants to offer me the ‘best,’ I sit up and pay attention.

I quickly learned this email was sent to me from the Canadian Breast Cancer Foundation as part of their monthly update. The email was essentially reminding me about how important breast cancer screening is and how often women should subject themselves to it.

“Mammograms save lives” read the headline. My heart sank. Not only is this headline unlikely to be true, it’s possibly dangerous. The headline followed with the statistic that “regular mammograms for women age 40 and over equal a 25 per cent reduction in the number of breast cancer-related deaths.”

Many scientists who have looked closely at the evidence have soundly questioned routine mammograms for healthy women (those with no extra risk factors for the disease), and particularly for younger women (those between ages 40 and 59) because of the very real problems of overdiagnosis and overtreatment.

So why is an organization dedicated to this serious condition sending out such misinformation – and why now, I wondered? Because, as the email says: “There appears to be much information of late in popular media about who should go [for screening] and how often.”

In other words, perhaps they felt it was time to counter what the scientists were saying. It was three years ago in the Canadian Medical Association Journal when Danish screening expert Dr. Peter Gotzsche asked a provocative question: Which country was going to be the first one to stop mammography? He was also the lead author of a Cochrane Review of mammography which included seven trials involving 600,000 women between 39 to 74 yearsrandomly assigned to receive screening mammograms or not and found that the screening did not reduce breast cancer deaths.

Then last February, a 25-year study by Cornelia Baines and Anthony Miller at the Dalla Lana School of Public Health in Toronto added weight to that assessment, finding that annual breast cancer screening of women age 40 and 59 does not reduce breast cancer death rates compared to regular physical examination or usual care. This message got a fair bit of media play because it was, after all, a Canadian study and one of the biggest and highest quality studies ever done on breast cancer screening.

This research is adding up to what I would call a wholesale re-questioning of the need for mammography based on the fact that the overall benefits seem to be vanishingly small and the harms – including unnecessary cancer scares, biopsies and surgeries — considerable.

Just two weeks ago, an article from the New England Journal of Medicine was published suggesting that Switzerland might be the first nation in the world to dismantle its breast cancer screening program for women of average risk. In a report prepared by the Swiss Medical Board (a group that assesses medical technology), the authors wrote that mammography screening of women between 50 and 69 may prevent one breast cancer death out of a 1,000 screened women, but that there was no proof that screening programs affect overall deaths. In other words, echoing the work of scientists like Baines, Miller and Gotzsche, the mantra that “Mammography Saves Lives” is simply not true for most women.

The authors of that recent New England article concluded by saying: “It is easy to promote mammography screening if the majority of women believe that it prevents or reduces the risk of getting breast cancer and saves many lives through early detection of aggressive tumours. We would be in favour of mammography screening if these beliefs were valid. Unfortunately, they are not, and we believe that women need to be told so.”

But what do Canadians get instead?

The Canadian Breast Cancer Foundation saying we should ignore the science, as they dish out the “Best Health Advice” via an email on a Friday afternoon.

Alan Cassels is an expert advisor with, a pharmaceutical policy researcher and the Author of Seeking Sickness: Medical Screening and the Misguided Hunt for Disease, which has an entire chapter devoted to the breast cancer screening debate.

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Category: Health

Comments (3)

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  1. Paula Gordon says:

    Mr. Cassels, a pharmaceutical policy researcher, has weighed in on screening mammography. He does women a disservice. He quotes only the 25-year update of the Canadian National Breast Screening trial, and does not include the fact that this was the ONLY trial of mammography screening that didn’t show decreased mortality. It is an outlier, and in 2002, the World Health Organization determined that it should be disregarded in in future considerations of the benefit of mammography. The flaws in the Canadian trial have been documented ad nauseum. But every 5 years they publish an update and cause a media frenzy and confusion for women.

    When the results of better trials are averaged, women invited to have mammography showed reduced death from breast cancer of 25-30%. More importantly, in women who actually have mammograms (many women invited in trials do not, but are still counted in the mammogram group when deaths are counted!) the mortality reduction is in the 40-50% range.

    But Mr. Cassels, whose declared conflict of interest is in selling his anti-screening book, says that promoting mammography is possibly dangerous. He quotes the harms of overdiagnosis and overtreatment, and cites Dr. Peter Gotschze and the Cochrane review, which have been roundly criticized by authorities in public health, epidemiology and statistics from all over the world because of their manipulation of data. Gotschze cherry-picked studies that supported his hypothesis, and disregarded favourable studies, based on his misunderstanding of the methodology of cluster randomization in screening trials.

    Mammography is not perfect. It doesn’t find all cancers, and when women are recalled when we find something on a mammogram that needs more tests, there is unavoidable transient anxiety and even sometimes a needle biopsy done with freezing to rule out cancer. But women know that this is reasonable, and would choose to have the test rather than let a patronizing administration decide that they should be spared the anxiety, and lose the opportunity to find a small cancer.

    Canadians deserve to hear the truth, not Mr. Cassels slagging the Canadian Breast Cancer Foundation. They appear to have a better understanding of the science than he does. He should stick to his area of expertise.

    Paula Gordon, OBC, MD, FRCPC, FSBI
    Clinical Professor, University of British Columbia

  2. Professor emeritus Laszlo Tabar says:

    Mr. Alan Cassels has a bias against early detection to promote his anti-screening book; he also admires Dr. Gøtzsche from Denmark who has a published bias against “all forms of screening” (Lancet 1997). Dr. Gøtzsche has never had access to individual patient data, he does not know which woman was or was not screened, or, even if a breast cancer was diagnosed in a woman who did or did not get a mammogram. How can one assess the impact of screening then? He and Dr. Welch from the USA offer women statistical manipulation weakened by missing facts. Why do these people want to throw women back to the Middle Ages when all breast cancers were huge, often ulcerated and most of them died from the disease. These gentlemen and Dr. Tony Miller, the leader of the flawed “Canadian trials” (trials considered by Prof Paula Gordon from Vancouver a “national embarrassment”) never mention the eight properly carried out randomized controlled trials that unequivocally proved that early detection decreases breast cancer death significantly. I wonder why the anti-screening campaign comes from a country with a shameful “study” and from Denmark where breast cancer death is the third highest in Europe. Something must be wrong with these people; we expect women stand up for their cause. We recommend that Mr. Cassels, a pharmaceutical policy researcher restricts his activities to his area of expertise.

    Professor emeritus Laszlo Tabar, MD, FACR(Hon)

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