COLUMBIA – About one in eight women will develop some kind of invasive breast cancer in her lifetime, according to the American Cancer Society. Finding those cancers isn’t always easy, especially with the current technology used to screen for them.
Conventional mammograms have been plagued for years by concerns of false positives. In regular digital scans, images of breast tissue can overlap, creating the illusion of a tumor where none exists. These false positives can come at a heavy price. A statistical model by the U.S. Preventive Services Task Force suggests that for every 1,000 women who receive a mammogram between ages 40 and 49, only one death from cancer is averted.
Separately, the National Cancer Institute found that each year, approximately 10 percent of women will be called back after their breast cancer screening for further testing, and only half of those women will actually have cancer.
When mammograms return evidence of cancer that isn’t there, it can cause bigger problems. Women may be subject to further, invasive procedures like breast biopsies. Some women even receive treatments that they didn’t need, like chemotherapy and radiation, which can cause further harm.
Dr. Terry Elwing is a radiologist and breast cancer imaging specialist at Boone Hospital, and she thinks it’s important to decrease the rate of falsely diagnosed breast cancer to save women from unnecessary anxiety.
“One of the things women fear most is getting called back for more testing,” she said.
There are different schools of thought about reducing over-diagnosis of breast cancer. Some medical professionals focus on limiting the number of potential screenings women have in their lifetime; some others hope to improve the screening technology to limit the number of false positives.
Delaying the age for mammograms
One approach is to delay the age when women start getting mammograms. In January 2016, the U.S. Preventive Services Task Force suggested that women with no other risk factors, start getting biennial mammograms at age 50, rather than 40. Women in their 40s should decide whether to do the screening with their doctors.
The American Cancer Society also recently changed its recommendations for mammograms, suggesting women start getting them annually, at age 45, instead of 40. Both sets of recommendations leave the decision to go through the diagnostic testing earlier up to the discretion of women and their doctors.
Dr. Kirsten Bibbins-Domingo is the professor of medicine and of epidemiology and biostatistics at the University of California, San Francisco and the chair of the Task Force. She said the recommendations reflect the best balance of odds for women.
Essentially, the Task Force found that while mammography did help reduce deaths from breast cancer for women between 40 and 74, the screenings were more worth the potential harms for women between 50 and 74, she said. Additionally, those women got the best balance of benefits and harms when they only got mammograms every two years.
In 2013, a study published in the Cochrane Review, which researches healthcare issues and offers recommendations, cast doubt on the effectiveness of mammograms over all; the study authors were able to anticipate that for 2,000 women between 39 and 74 given mammograms for 10 years, only one woman would avoid death from cancer and 10 would receive unnecessary treatment of some kind.
However, healthcare providers don’t always accept those recommendations. In fact, medical organizations including the American College of Radiology, the American Medical Association and the American College of Obstetricians and Gynecologists, all still recommend screening starting at age 40. Some doctors also take issue with the Task Force’s recommendation of women having mammograms every other year, instead of annually.
Elwing is a member of the American College of Radiology. In a statement, the organization said the Task Force’s recommendation “ignor[es] direct scientific evidence.”
JoAnn Franklin has worked in healthcare in different rural towns around Missouri for most of her life as a nurse practitioner and researcher. Franklin said she believes that even if earlier mammograms detected just one more legitimate case of cancer a year, they would be worth it.
“I just think that if we have the ability to screen for an illness that could save someone’s life or make their life much easier by early detection, that it’s a good thing,” she said. “I just don’t think that age always makes a difference in findings.”
Dr. Megha Garg is the director of breast imaging at the Ellis Fischel Cancer Center, associated with the University of Missouri hospital system, and she would generally prefer her patients get mammograms starting at age 40.
“I think we should take those recommendations with a grain of salt,” Garg said. “Right now the recommendations are not geared toward saving lives. They’re geared toward saving resources. We see a lot of young cancer patients in their 40s, and if we were to see that in two or four more years, we can’t really treat it.”
However, Bibbins-Domingo said the Task Force was focused on avoiding unnecessary harms, not saving resources. The recommendations are intended help doctors and patients decide together if potential risks from screening are worth it, she said.
Generally, the Task Force recommendations set the stage for what will and won’t be covered by insurance under the Affordable Care Act, but that’s not the case for mammograms. There is a specific caveat written so that women in their 40s can still be covered for mammograms if they choose.*
If women choose to be screened after they turn 40, their insurance must pay for it. Medicare provides similar diagnostic coverage for women who qualify.
Using new technology
Another way to help avoid false positives from mammograms? Better technology. Tomosynthesis, or 3D mammography, gives doctors a much better view of breasts, and helps eliminate false positives. It’s one significant innovation in mammogram technology.
While traditional digital mammograms take X-rays from the front and sides of a breast, 3D mammogram tools measure the breast tissue in slices. These individual slices don’t overlap the way the images from traditional digital mammograms do, so there is less chance of the images showing a mass where none exists.
Elwing estimates that the first year a facility uses 3D mammography, its doctors can see between a 15 and 20 percent decrease in falsely diagnosed cases of breast cancer. The FDA found a 7 percent improvement in accurate readings using 3D mammograms over traditional digital ones.
Approved by the FDA in 2011, 3D mammography gives healthcare providers the ability to catch smaller, more invasive tumors that traditional mammograms can miss.
“We find more cancers, we find smaller cancers, and the cancers we’re finding are invasive cancers, which are the cancers you want to find,” Elwing said.
However, as with any new technology, the increased sensitivity and accuracy of 3D mammography comes with some trade-offs. For one thing, the 3D tests do expose women to higher doses of radiation, although Elwing said the radiation for both kinds of mammograms is less than you’re exposed to on a cross-country airplane ride.
Additionally, the tests create many more scans, which take radiologists more time to read. When Boone Hospital first installed the 3D equipment, the radiologists worked the extra time and the hospital didn’t pass the additional cost onto patients. Today, the hospital charges a maximum of $25 more for 3D mammograms than traditional ones, if the cost isn’t covered by insurance.
“It does take about twice as long to read one, but we feel that’s what the patient deserves,” Elwing said. “That’s what I’d want.”
As 3D mammograms become more common, they’re covered by more and more insurance plans, the same way traditional digital mammograms are. Medicare covers 3D mammograms as of this year, and Elwing estimates that about 50 percent of private insurers now include 3D mammograms as well. There are currently four facilities in Columbia, Missouri that offer the screening.
The Ellis Fischel Cancer Center at the University of Missouri Hospital is working to make more these mammogram machines available to women in rural Missouri as soon as possible. The hospital has offered a mammography van since 2005, but in April, the providers updated the van with new 3D equipment.
This van works as a stop-gap solution for women who live in small towns and don’t have access to typical screening services. Garg is especially proud of the updated van, which performed almost 3,000 screenings in 49 Missouri counties in 2015. She hopes the new van will screen at least as many women and with higher accuracy.
“In rural areas, it’s not just providing a breast service, it’s providing the best service,” she said.
*UPDATE: Information about insurance coverage is available on the USPTF website.