Unpicking some of the ongoing debate around breast cancer screening
When the histories of modern medicine are written, surely the case of screening mammography will be one of the more fascinating chapters.
The story of its enthusiastic promotion and uptake, followed by a steadily mounting and widening chorus of concern about how the benefits and harms stack up up, can be explored through so many prisms.
I’m not sure how neatly it might fit into the framework of Gartner’s hype cycle**, (as per the diagram on the left, sourced from Wikipedia), although it seems we’ve passed “the peak of inflated expectations”.
The article below is cross posted from Gary Schwitzer and the excellent Health News Review site in the US, examining some of the reaction to a study recently published in the New England Journal of Medicine.
The researchers estimate that breast cancer was overdiagnosed (ie tumors were detected on screening that would never have led to clinical symptoms) in 1.3 million US women in the past 30 years.
They estimate that in 2008 breast cancer was overdiagnosed in more than 70,000 women in the US, accounting for 31 percent of all breast cancers diagnosed.
Just to underline – the study was examining screening mammography, not the diagnostic use of the technology. It is not a randomised controlled trial.
Interestingly, one of the researchers, Professor Gilbert Welch, has explained the findings in simple terms in a YouTube clip (as per the link in the post).
(As an unrelated aside, I wonder how widely researchers are using YouTube – whether to share or defend their results, encourage uptake into practice and policy, or to increase citations?)
Roundup of some reactions to NEJM mammography overdiagnosis analysis
Gary Schwitzer writes:
There has been much reaction to a paper in the New England Journal of Medicine, “Effect of Three Decades of Screening Mammography on Breast-Cancer Incidence.”
It is at times like this that a lone blogger like me on a holiday weekend can easily feel overwhelmed by the enormity of the task of trying to capture the discussion with accuracy, balance and completeness. With that caveat, I make a humble and admittedly limited attempt.
First, interested readers should not miss the NEJM forum offering a poll and comments section after posing a case vignette of a 40-yar old woman and the mammography decision and this:
Which one of the following approaches do you find appropriate for women who, like the woman in the vignette, are at average risk? Base your choice on the published literature, your own experience, recent guidelines, and other sources of information, as appropriate.
Option 1: Recommend Screening Mammography Starting at the Age of 40
Option 2: Recommend Screening Mammography Starting at the Age of 50
Option 3: Do Not Recommend Screening Mammography
Dr. Gil Welch, one of the authors of the “Effect of Three Decades…” analysis, wrote a New York Times opinion piece, “Cancer Survivor or Victim of Overdiagnosis?” in which he summarized:
“So here is what we now know: the mortality benefit of mammography is much smaller, and the harm of overdiagnosis much larger, than has been previously recognized.
But to be honest, that general message has been around for more than a decade. Why isn’t it getting more traction?
The reason is that no other medical test has been as aggressively promoted as mammograms — efforts that have gone beyond persuasion to guilt and even coercion (“I can’t be your doctor if you don’t get one”).
And proponents have used the most misleading screening statistic there is: survival rates. A recent Komen foundation campaign typifies the approach: “Early detection saves lives. The five-year survival rate for breast cancer when caught early is 98 percent. When it’s not? It decreases to 23 percent.”
Survival rates always go up with early diagnosis: people who get a diagnosis earlier in life will live longer with their diagnosis, even if it doesn’t change their time of death by one iota. And diagnosing cancer in people whose “cancer” was never destined to kill them will inflate survival rates — even if the number of deaths stays exactly the same. In short, tell everyone they have cancer, and survival will skyrocket.
Screening proponents have also encouraged the public to believe two things that are patently untrue.
First, that every woman who has a cancer diagnosed by mammography has had her life saved (consider those “Mammograms save lives. I’m the proof” T-shirts for breast cancer survivors). The truth is, those survivors are much more likely to have been victims of overdiagnosis.
Second, that a woman who died from breast cancer “could have been saved” had her cancer been detected early. The truth is, a few breast cancers are destined to kill no matter what we do.”
Dr. Len Lichtenfeld wrote on the American Cancer Society blog, “Breast Cancer Screening: The Search for Truth.” Excerpt:
“We live in a headline driven world. The role of mammography for women is not immune to that influence. There will be many, many headlines on this topic, but too few folks will actually read the body of the article. And there is no telling how the body of any particular media article is going to portray the story, whether it be written to scare women or provide them with accurate information.
There is no way to tell how women are going to make up their minds to get screened or not get screened for breast cancer, but I can bet you there are going to be some who see the headlines and decide that mammography is not for them. Unfortunately, the researchers can’t tell them whether or not they made the right decision for themselves as an individual. We just don’t have the science to answer that question for any individual woman. So it comes down to basic facts: until science supplies us with the accurate answer, each woman has to make a decision regarding screening mammography. Hopefully that decision will be an informed one through discussion with a knowledgeable health professional in conjunction with reliable information available from other sources (such as the American Cancer Society at www.cancer.org).
Many of us are concerned that women will read or hear the headline and forego screening mammograms altogether. We at the American Cancer Society – and I suspect many other experts-do not believe that would be the right approach. At least pick a suggested screening program that is right for you. We would recommend our guidelines, but we recognize there are others.
But at the end of the day, do not believe that the message delivered today is the end of the discussion. It is not. There was a different message delivered in other research papers last month, as there have in years past and will be in years to come until we get the scientific answers and guidance we need.
The search for the truth must continue unabated. Too many lives depend on it.”
And then there are our readers. One of them, Dr. Bradley Flansbaum, hospitalist and blogger at The Hospitalist Leader, sent us his comments:
“The trial looked at the 30-year increase in early breast cancer diagnosis with the 1980′s introduction of mammograms, without a concurrent drop in late stage illness (overdiagnosis). My criticism however, stems from the NPR/Kaiser Health News coverage the study received.
I am very bothered over this passage: (Note from Croakey, the text in bold below is from the NPR/Kaiser Health News report.)
The ACR (American College of Radiology) statement’s main criticism is that Welch and Bleyer don’t account for what the radiologists say was a steady increase in the incidence of invasive breast cancer. They say that can explain why mammography didn’t lower the incidence of advanced breast cancer more.
Welch rejects that claim. “Why was breast cancer incidence so stable in the late ’70s, only to shoot up in the 1980s – the very time mammography was introduced?” he writes in an email. “Why didn’t incidence rise dramatically in women under 40 — those not exposed to screening?”
Welch is no newcomer to debates over the benefits and harms of diagnostic screening tests. In fact, he’s a well-known iconoclast, who last year published the popular book Overdiagnosed: Making People Sick in the Pursuit of Health.
“He has a preexisting bias, just as those of us in the breast imaging community have a preexisting bias,” Lee says. “The truth probably lies somewhere in between.”
(Note from Croakey, the text that follows is a continuation of Dr Flansbaum’s own comments)
Welch’s analysis was a large trial published in a peer reviewed journal. What evidence does Dr. Lee offer to counter the findings of Dr. Welch, other than an increase in “invasive breast cancer” and “bias”? A false equivalence through my lens, and I see no references or push back from the journalist. Dr. Lee’s contention may be true, but if you wish to rebut the conclusions of the work, bring or research your own. More to the point, convey this to the reader.
She concludes with, “The truth probably lies somewhere in between.”
Addendum on November 25: Dr. Welch has posted an explanatory video on YouTube, “NEJM Screening Mammography – Understanding the Research.”
Addendum on November 28: The New York Times published a letter to the editor, “The Value of Mammograms,” from nine doctors and one nurse who wrote:
“We who battle breast cancer daily are horrified by H. Gilbert Welch’s repeated attacks on screening mammograms (“Cancer Survivor or Victim of Overdiagnosis?” Op-Ed, nytimes.com, Nov. 22). Would he have us return to the era when tumors were discovered only when they were large enough to be felt, meaning more disfiguring surgery, prolonged chemotherapy and lower cure rates?
His flawed reanalysis of old data lacks actual screening information, applies arbitrary adjustments for hormone use and makes an unjustified assumption that breast cancer incidence is not truly rising.
In contrast, prospective randomized trials of mammography have been reviewed and accepted globally: screened women have smaller, more curable cancers that are treatable with cosmetically superior surgery and less toxic medical therapy.
Early diagnosis and better treatment are partners. Would Dr. Gilbert, or any rational person, ignore a likely cancer on a mammogram and wait until it grows into a large mass while it possibly spreads throughout the body?”
But Dr. David Newman’s piece on the NYT website, “Ignoring the Science on Mammograms,” stated:
“It is affirming to see this newest study. But it raises an awkward question: why would a major medical journal publish an observational study about the effects of screening mammography years after randomized trials have answered the question? Perhaps it is because many doctors and patients continue to ignore the science on mammograms.
For years now, doctors like myself have known that screening mammography doesn’t save lives, or else saves so few that the harms far outweigh the benefits. Neither I nor my colleagues have a crystal ball, and we are not smarter than others who have looked at this issue. We simply read the results of the many mammography trials that have been conducted over the years. But the trial results were unpopular and did not fit with a broadly accepted ideology—early detection—which has, ironically, failed (ovarian, prostate cancer) as often as it has succeeded (cervical cancer, perhaps colon cancer).
More bluntly, the trial results threatened a mammogram economy, a marketplace sustained by invasive therapies to vanquish microscopic clumps of questionable threat, and by an endless parade of procedures and pictures to investigate the falsely positive results that more than half of women endure. And inexplicably, since the publication of these trial results challenging the value of screening mammograms, hundreds of millions of public dollars have been dedicated to ensuring mammogram access, and the test has become a war cry for cancer advocacy. Why? Because experience deludes: radiologists diagnose, surgeons cut, pathologists examine, oncologists treat, and women survive.
Medical authorities, physician and patient groups, and ‘experts’ everywhere ignore science, and instead repeat history. Wishful conviction over scientific rigor; delusion over truth; form over substance.”
• This article was first published at Health News Review
And the view from Australia?
These articles were both published before the NEJM study:
• Professor Ian Olver from Cancer Council Australia: The benefits of breast cancer screening outweigh the problems.
• A recent article by researchers Professor Alexandra Barratt and Ray Moynihan: Cancer’s other risk, overdiagnosis
Disclaimer: Croakey is a place for sharing ideas and discussions – it does not intend to provide personal health advice. If this or any articles raise personal health issues or concerns for you, please seek expert advice. And you might like to consider asking the questions suggested in this book, Smart Health Choices, available on free download.
** And, finally, thanks to Jenny Brands, of the Menzies School of Health Research, whose recent presentation at Congress Lowitja introduced me to the concept of Gartner’s Hype Cycle. Wish I’d known about it years ago….
(Note from Croakey, 1 December: This post was edited to provide greater clarity in the formatting.)