Skip to main content

Mammograms can help--and harm

By H.Gilbert Welch
updated 8:49 AM EST, Wed November 20, 2013
H. Gilbert Welch says mammograms don't always save lives, can lead to unnecessary surgery, chemotherapy and/or radiation.
H. Gilbert Welch says mammograms don't always save lives, can lead to unnecessary surgery, chemotherapy and/or radiation.
STORY HIGHLIGHTS
  • Gilbert Welch: Amy Robach had double mastectomy when mammogram revealed cancer
  • She says mammogram saved her life; he says that's not how it works. Cancers all different
  • He says cancers may be very slow; early discovery may lead to unneeded harmful treatment
  • Welch: Study: Women 3 times more likely to be overdiagnosed than to have "life saved"

Editor's note: H. Gilbert Welch is a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice and a co-author of "Overdiagnosed: Making People Sick in the Pursuit of Health."

(CNN) -- I don't want to write this.

As part of breast cancer awareness month, a 40-year-old anchor had her first mammogram on morning television. And last week the anchor, Amy Robach, underwent a double mastectomy after announcing she had cancer, and saying -- in front of 5 million viewers -- that "having a mammogram saved my life."

And I feel the obligation to point out that other possibilities are more likely.

To understand why, you need to know how doctors now think about cancer: in terms of turtles, rabbits and birds. The goal is not to let any of the animals escape the barnyard pen to become deadly. But the turtles aren't going anywhere anyway. They are the indolent, nonlethal cancers. The rabbits are ready to hop out at any time. They are the potentially lethal cancers, cancers that might be stopped by early detection and treatment. Then there are the birds. Quite simply, they are already gone. They are the most aggressive cancers, the ones that have already spread by the time they are detectable, the ones that are beyond cure.

H. Gilbert Welch
H. Gilbert Welch

Before I go through the other possibilities, let me be clear about something: I know Robach has been through an emotionally gut-wrenching month. I know she is worried about her children. I know her parents are worried about her. And I truly hope the mammogram served a purpose -- that it saved her life.

It is understandable that any woman with a screening-detected cancer would want to believe this. But all women contemplating mammography should understand the other possibilities.

One possibility is that it could not save a life, that the woman will ultimately die from her disease. Thankfully this possibility is the least likely. Yet in every trial of screening, some women die from breast cancer despite its being detected early. It's not the mammogram's fault, it's the bird's fault. The birds are the reason why the rate at which women present with metastatic breast cancer in the United States remains unchanged, despite three decades of widespread screening mammography.

Another possibility is that early detection was unnecessary -- that she could have done just as well had her cancer progressed to the point she noticed a breast lump. Doctors are getting pretty good at dealing with rabbits. While the news media tends to focus on screening, the bigger story in breast cancer is the dramatic improvement in treatment over the last 20 years. Ironically, the better we are at treating breast cancer -- the less important it is to screen for it.

The final possibility is that she was overdiagnosed -- diagnosed with a cancer that may not have been destined to ever bother her. Cancer biologists now recognize that small collections of abnormal cells may meet the pathological criteria for cancer, yet never progress to affect the patient. In other words, her cancer may have been a turtle: it may not have been going anywhere anyway. While doctors used to debate whether turtles really existed in breast cancer, now the debate is about how many turtles exist.

Even the program that promotes screening mammography in the United Kingdom now acknowledges that women are three times more likely to be overdiagnosed than they are to have their "life saved."

Sambolin: Angelina gave me courage
Foods to help fight breast cancer

Some researchers think the overdiagnosed to lives-saved ratio is closer to 10 to 1.

Others might argue it's considerably less. Overdiagnosis is notoriously difficult to quantify. But most agree overdiagnosis is more common than having your life saved.

That nuance is lost in the powerful survivor stories that appear regularly in the media. Of course, everyone wants to interpret them as evidence of the benefit of mammograms. Unfortunately, the more likely interpretation is that they represent evidence of harm: unnecessary surgery, chemotherapy and/or radiation.

Why is this important? Video images of individuals purported to be helped exaggerate the benefit of mammography, while hiding its harms. They impede efforts to balance the process, such as screening less frequently or starting later in life. And they give more weight to the idea that the way to deal with cancer is to find more of it.

Why don't I want to write this? Because no one wants to dispute the interpretation of a well-meaning cancer patient who is trying to help people. And no one wants to make a difficult situation any harder. But news stories about health -- particularly on television -- are too driven by powerful personal anecdotes. The public deserves more nuance.

Follow us on Twitter @CNNOpinion.

Join us on Facebook/CNNOpinion.

The opinions expressed in this commentary are solely those of H. Gilbert Welch

ADVERTISEMENT
Part of complete coverage on
updated 11:30 PM EST, Sun December 28, 2014
Les Abend: Before we reach a conclusion on the outcome of AirAsia Flight QZ8501, it's important to understand that the details are far too limited to draw a parallel to Flight 370
updated 8:27 PM EST, Fri December 26, 2014
The ability to manipulate media and technology has increasingly become a critical strategic resource, says Jeff Yang.
updated 11:17 AM EST, Fri December 26, 2014
Today's politicians should follow Ronald Reagan's advice and invest in science, research and development, Fareed Zakaria says.
updated 8:19 AM EST, Fri December 26, 2014
Artificial intelligence does not need to be malevolent to be catastrophically dangerous to humanity, writes Greg Scoblete.
updated 10:05 AM EST, Fri December 26, 2014
Historian Douglas Brinkley says a showing of Sony's film in Austin helped keep the city weird -- and spotlighted the heroes who stood up for free expression
updated 8:03 AM EST, Fri December 26, 2014
Tanya Odom that by calling only on women at his press conference, the President made clear why women and people of color should be more visible in boardrooms and conferences
updated 6:27 PM EST, Sat December 27, 2014
When oil spills happen, researchers are faced with the difficult choice of whether to use chemical dispersants, authors say
updated 1:33 AM EST, Thu December 25, 2014
Danny Cevallos says the legislature didn't have to get involved in regulating how people greet each other
updated 6:12 PM EST, Tue December 23, 2014
Marc Harrold suggests a way to move forward after the deaths of NYPD officers Wenjian Liu and Rafael Ramos.
updated 8:36 AM EST, Wed December 24, 2014
Simon Moya-Smith says Mah-hi-vist Goodblanket, who was killed by law enforcement officers, deserves justice.
updated 2:14 PM EST, Wed December 24, 2014
Val Lauder says that for 1,700 years, people have been debating when, and how, to celebrate Christmas
updated 3:27 PM EST, Tue December 23, 2014
Raphael Sperry says architects should change their ethics code to ban involvement in designing torture chambers
updated 10:35 PM EST, Tue December 23, 2014
Paul Callan says Sony is right to call for blocking the tweeting of private emails stolen by hackers
updated 7:57 AM EST, Tue December 23, 2014
As Christmas arrives, eyes turn naturally toward Bethlehem. But have we got our history of Christmas right? Jay Parini explores.
updated 11:29 PM EST, Mon December 22, 2014
The late Joe Cocker somehow found himself among the rock 'n' roll aristocracy who showed up in Woodstock to help administer a collective blessing upon a generation.
updated 4:15 PM EST, Tue December 23, 2014
History may not judge Obama kindly on Syria or even Iraq. But for a lame duck president, he seems to have quacking left to do, says Aaron Miller.
updated 1:11 PM EST, Tue December 23, 2014
Terrorism and WMD -- it's easy to understand why these consistently make the headlines. But small arms can be devastating too, says Rachel Stohl.
updated 1:08 PM EST, Mon December 22, 2014
Ever since "Bridge-gate" threatened to derail Chris Christie's chances for 2016, Jeb Bush has been hinting he might run. Julian Zelizer looks at why he could win.
updated 1:53 PM EST, Sat December 20, 2014
New York's decision to ban hydraulic fracturing was more about politics than good environmental policy, argues Jeremy Carl.
updated 3:19 PM EST, Sat December 20, 2014
On perhaps this year's most compelling drama, the credits have yet to roll. But we still need to learn some cyber lessons to protect America, suggest John McCain.
updated 5:39 PM EST, Mon December 22, 2014
Conservatives know easing the trade embargo with Cuba is good for America. They should just admit it, says Fareed Zakaria.
updated 8:12 PM EST, Fri December 19, 2014
We're a world away from Pakistan in geography, but not in sentiment, writes Donna Brazile.
updated 12:09 PM EST, Fri December 19, 2014
How about a world where we have murderers but no murders? The police still chase down criminals who commit murder, we have trials and justice is handed out...but no one dies.
updated 6:45 PM EST, Thu December 18, 2014
The U.S. must respond to North Korea's alleged hacking of Sony, says Christian Whiton. Failing to do so will only embolden it.
updated 4:34 PM EST, Fri December 19, 2014
President Obama has been flexing his executive muscles lately despite Democrat's losses, writes Gloria Borger
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT