Danish Study Raises More Questions About Mammograms' Message | KERA News

Danish Study Raises More Questions About Mammograms' Message

Jan 9, 2017

For years, women have been told that regular mammograms can help reduce their risk of dying from breast cancer by catching tumors at their earliest, most treatable stages.

But a Danish study is the latest research to challenge that assumption. Researchers followed thousands of women in Denmark over more than a decade and found that perhaps one-third of the abnormalities detected by mammograms may never cause health problems.

"Breast screening can have some very substantial harms," says Karsten Jorgensen, deputy director of the Nordic Cochrane Centre in Denmark, who led the study. "And the most important one of those is the overdiagnosis of breast cancers that would never have developed into something life-threatening."

The study adds to growing evidence that breast cancer screening can lead to unneeded treatment.

"There's a tendency in the United States to think that screening is better than it actually is," says Otis Brawley, chief medical officer at the American Cancer Society. Brawley wrote an editorial accompanying the study.

"It's important that we learn the limitations of screening so that we can apply that tool as best we possibly can to save as many lives as possible," Brawley says.

The problem, Brawley says, is that doctors can't yet tell which tumors really need to be treated and which they might be able to just monitor. For now, he says, it's important all women continue to follow mammography guidelines and get treated if they are diagnosed.

"One of my nightmares is people will read this paper," Brawley says, and "elect to not get treated."

The cancer society's guidelines say mammograms should be an option starting at age 40, and that annual mammograms should start at age 45. At age 55, women can cut back to every two years, according to the guidelines. Another group, the U.S. Preventive Services Task Force, advises that regular biennial mammograms start at age 50.

But others argue the paper should encourage women to think twice about whether they need a mammogram.

"Women should understand all of these issues and make their own decision if they want to have a mammogram," says Fran Visco of the National Breast Cancer Coalition, an advocacy group. "They should really think very carefully before getting a mammogram."

And other researchers dismissed the findings, saying the new study is flawed and that there is clear evidence mammograms save lives.

"It's giving women the wrong idea that half of all cancers maybe are nothing to worry about," says Debra Monticciolo, who is chairwoman of the American College of Radiology's Breast Imaging Commission. "Nothing could be further from the truth."

The study, published in Annals of Internal Medicine, took advantage of an unusual situation. Denmark made screening mammography available to all women at different times in different parts of the country. That enabled the researchers to compare the incidence of early- and late-stage breast cancer in different regions, comparing those who got mammograms and those who didn't.

"We wanted to look at whether breast screening led to fewer advanced-stage cancers because screening is really based on the premise that you detect cancer earlier so you should have less advanced cancers over time," Jorgensen says.

But the analysis found that there was no "reduction in the frequency of late-stage tumors in the screened areas compared to the non-screened areas," Jorgensen says. "But we did see a huge increase in the occurrence of early-stage cancers."

The findings suggest mammograms are frequently picking up lumps that would never become a health problem. Like many prostate cancers, they may never grow or may even regress on their own.

"That means that these essentially healthy women get a breast cancer diagnosis that they otherwise would never have gotten," says Jorgensen. "It's really a life-changing event to get a cancer diagnosis."

In addition to causing stress and anxiety, a breast cancer diagnosis also usually leads to treatment, which can include surgery, radiation and chemotherapy, which are difficult and can have serious side effects.

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AUDIE CORNISH, HOST:

There's another twist in the debate over the value of routine mammograms. A new study finds one-third of the lumps detected by mammograms may be nothing to worry about. NPR health correspondent Rob Stein has details.

ROB STEIN, BYLINE: For years, women have heard that mammograms save lives by catching tumors early before they become life threatening. But Karsten Jorgensen of the Nordic Cochrane Centre in Denmark wanted to find out is that really true?

KARSTEN JORGENSEN: We wanted to look at whether breast screening led to fewer advanced stage cancers because screening is really based on the premise that you detect cancer earlier so you should have less advanced cancers over time.

STEIN: So Jorgensen's team analyzed what happened in Denmark over about a decade as routine mammograms were phased in around the country to screen for breast cancer.

JORGENSEN: We didn't see any reduction in the frequency of late stage tumors in the screened areas compared to the unscreened areas. But we did see a huge increase in the occurrence of early staged cancers.

STEIN: Jorgensen says that suggests mammograms are often just picking up lumps that never would end up causing any problems. In fact, he calculates that around one-third of the abnormalities that get flagged by mammograms are really nothing to worry about.

JORGENSEN: That means that these essentially healthy women get a breast cancer diagnosis that they otherwise would never have gotten.

STEIN: Jorgensen says that has some really profound implications.

JORGENSEN: It's really a life changing event to get a cancer diagnosis. And it leads to some treatment, of course, surgery, radiotherapy, sometimes chemotherapy that we know have harms and sometimes serious harms.

STEIN: Some other experts agree that the power of mammograms probably has been overestimated. Otis Brawley is the chief medical officer at the American Cancer Society.

OTIS BRAWLEY: I think there's a tendency in the United States to think that screening is better than it actually is. And I think that it's important that we learn the limitations of screening so that we can apply that tool as best we possibly can to save as many lives as possible.

STEIN: The problem, Brawley says, is that doctors can't yet tell which tumors they really need to treat and which they might be able to just keep an eye on. So for now Brawley says it's important all women continue to follow mammography guidelines and get treated if they get diagnosed.

BRAWLEY: One of my nightmares is people will read this paper, which is about where we're moving science to, and assume that science is already there. And there are some women who might read this and elect not to get treated.

STEIN: Others argue that the paper should encourage women to really think twice about whether they need a mammogram in the first place. Fran Visco heads the National Breast Cancer Coalition, an advocacy group.

FRAN VISCO: Women should understand all of these issues and make their own decision if they want to have a mammogram. They shouldn't blindly follow slogans of early detections save lives, once a year for a lifetime. They should really think very carefully before getting a mammogram.

STEIN: But others dismiss the findings, saying the new study is flawed and they say there's clear evidence mammograms save lives. Debra Monticciolo is with the American College of Radiology.

DEBRA MONTICCIOLO: It's giving women the wrong idea that, you know, half of all cancers are maybe just are nothing to worry about. And nothing could be further from the truth.

STEIN: So one thing's clear. The debate over mammography is far from over. Rob Stein, NPR News. Transcript provided by NPR, Copyright NPR.