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Wed November 21, 2012
With Routine Mammograms, Some Breast Cancers May Be Overtreated
Originally published on Wed November 21, 2012 4:01 pm
The endless debate over routine mammograms is getting another kick from an analysis that sharply questions whether the test really does what it's supposed to.
Dr. H. Gilbert Welch, coauthor of the analysis of mammography's impact, which was just published in The New England Journal of Medicine, tell Shots that the aim was to "get down to a very basic question."
That is, do annual mammograms among women over 40 discover early-stage breast cancers that can be treated so that they never become deadlier late-stage tumors?
Welch, of Dartmouth Medical School, and coauthor Dr. Archie Bleyer of the Oregon Health and Science University, analyzed 30 years of data on breast cancer incidence.
"And what we see is a dramatic increase — a doubling — in the amount of early-stage cancer," Welch says. "But we don't see a corresponding decrease in the amount of late-stage cancer."
They say this means mammography isn't catching many advanced breast cancers — even though it's very good at catching early tumors.
Too good, perhaps. The duo says many of the early tumors revealed by mammography don't need to be treated at all. Doctors call that "overdiagnosis."
Welch says more than 1 million women have been overdiagnosed with breast cancer over the past 30 years. And the problem continues.
"Seventy thousand women a year are overdiagnosed and treated unnecessarily for breast cancer," Welch says.
This all may come as a shock to many women — and their doctors. No other diagnostic test has been more aggressively promoted than mammography — or, lately, been so controversial, with the possible exception of PSA tests for prostate cancer.
"Whenever I see a paper like this, I say, 'Oh, boy, here we go again!' " says Dr. Carol Lee, a breast-imaging specialist at Memorial Sloan-Kettering Cancer Center in New York City.
The ACR'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 pre-existing bias, just as those of us in the breast-imaging community have a pre-existing bias," Lee says. "The truth probably lies somewhere in between."
Still, Lee finds it hard to believe that 70,000 women a year are diagnosed with breast cancer that would not have progressed. And she says the debate isn't very helpful to most women.
"What my friends in Connecticut want to know is, 'Should I have a screening mammogram?' And ... this kind of study sometimes raises more questions than it answers," Lee says.
San Francisco breast surgeon Laura Esserman agrees that women are tortured by these endless debates. But she sees a way out of the dilemma.
"Our concept of cancer has got to change," she tells Shots. "We now recognize that there isn't just one pathway — it's not cancer, yes or no." And doctors know now that cancer doesn't always lead to death.
Esserman thinks mammography screening should be done more selectively. Women at lower risk of breast cancer — because they don't have close relatives who've had it or have a genetic predisposition for it — may not need to be screened so often.
Second, she says women and their doctors have to get out of the mind-set that any breast cancer should be treated maximally. For instance, doctors now routinely deploy surgery, hormones and radiation to treat a condition called ductal carcinoma in situ, or DCIS.
"We can watch a lot of those things and most of them turn out to be just fine," she says.
But this is a long way from how either mammography or breast cancer treatment is practiced right now.
AUDIE CORNISH, HOST:
From NPR News, this is ALL THINGS CONSIDERED. I'm Audie Cornish.
ROBERT SIEGEL, HOST:
And I'm Robert Siegel. Now, a new chapter in a long-running debate about the value of mammograms. Every year, American women get nearly 40 million of them; most of the time, to screen for unsuspected breast cancer. Well, a new analysis - out today, in "The New England Journal of Medicine" - looks at 30 years' worth of data. And as NPR's Richard Knox reports, it concludes that mammograms are leading thousands of women to get treated for breast cancer unnecessarily.
RICHARD KNOX, BYLINE: Dr. Gilbert Welch, of Dartmouth Medical School, says the purpose of the study was to get down to a very basic question: Do routine mammograms do what they're supposed to?
DR. GILBERT WELCH: For screening to work, it must take women who are destined to develop late-stage cancer, and find them when they're early-stage.
KNOX: So Welch and his colleague Dr. Archie Bleyer looked at what happened after mammography screening came into use, in the mid-1980s. They looked at how many women were diagnosed with early-stage breast cancer over the next three decades, and how many were diagnosed with late-stage cancer.
WELCH: And what we see is a dramatic increase - a doubling - in the amount of early-stage cancer. But we don't see a corresponding decrease in the amount of late-stage cancer.
KNOX: They say that means mammography isn't catching many advanced breast cancers, even though it's very good at catching early tumors. And moreover, they say many of the early tumors revealed by mammography, don't need to be treated at all. Doctors call that overdiagnosis. Welch says more than a million women have been overdiagnosed with breast cancer over the past 30 years, and the problem continues.
WELCH: Seventy thousand women a year are overdiagnosed, and treated unnecessarily, for breast cancer.
KNOX: This all may come as a shock to many women - and their doctors. No other diagnostic test has been more aggressively promoted than mammography; or lately, been so controversial.
DR. CAROL LEE: Whenever I see a paper like this, I say, oh, boy. Here we go again.
KNOX: That's Dr. Carol Lee. She's a mammography specialist at Memorial Sloan-Kettering Cancer Center, in New York City. She's also an official of the American College of Radiology, whose members do mammography. The college, in a statement, says the new analysis is simply wrong. Lee doesn't go quite that far, but she's highly skeptical.
LEE: I find it hard to believe that seven - what did they say? - 70,000 women in 2008 were diagnosed with breast cancer that would not have progressed? I just - I - I find that incredibly difficult to believe.
KNOX: Doctors will probably be arguing about the new study for some time. But Lee says the debate isn't very helpful to most women.
LEE: What my friends in Connecticut want to know is, should I have a screening mammogram? And I think this kind of study just really - sometimes raises more questions than it answers.
KNOX: San Francisco breast surgeon Laura Esserman agrees that women are tortured by these endless debates.
DR. LAURA ESSERMAN: They're caught in the middle. This is like two physicians fighting over how to treat a patient, and catching the patient in the middle. That's what's terrible. Shame on us.
KNOX: Esserman agrees that 20 to 30 percent of breast cancers diagnosed with mammograms, these days, are not life-threatening. But she sees a way out of this dilemma.
ESSERMAN: Our concept of cancer has got to change. We now recognize that there isn't just one pathway. It's not cancer - yes or no; and cancer that inexorably progresses to death.
KNOX: But highly sensitive mammograms pick up all kinds.
ESSERMAN: When you screen, you necessarily surface what we call idle lesions, or idle conditions. That is a consequence of screening. It doesn't make screening good or bad. So screening will be bad if we don't recognize these idle conditions, and we overtreat them.
KNOX: Esserman thinks mammography screening should be done more selectively. Women at lower risk of breast cancer - because they don't have close female relatives who've had it, or a genetic predisposition - may not need to be screened so often.
ESSERMAN: We're not going to screen our way into a cure. The most aggressive cancers show up in-between normal screens.
KNOX: Second, she says women and their doctors have to get out of the mindset that any breast cancer should be maximally treated. Currently, doctors routinely use surgery, hormones and even radiation to treat a condition called DCIS, ductal carcinoma in situ.
ESSERMAN: You know, we can watch a lot of those things. And most of those things turn out to be just fine.
KNOX: But this is a long way from how either mammography, or breast cancer treatment, is practiced right now.
Richard Knox, NPR News. Transcript provided by NPR, Copyright NPR.