An interview with Dr. Polly Stephen of Richmond’s Bon Secours on the difference between 2D and 3D mammography technology.
The Congregation of the Sisters of Bon Secours is a Roman Catholic religious congregation for nursing whose stated object is to care for patients from all socioeconomic groups. In Richmond, Virginia, they are also in the forefront of medicine with two of its local hospitals winning the 2018 Distinguished Hospital Award for Clinical Excellence.
Bon Secours women’s imaging center recently bought its first Digital or 3D mammogram machine for detecting breast cancer. “It costs women who want to use it alot – all out of pocket – and you’ll have to wait at least five months for your chance,” Dr. Polly Stephens explained. “There’s sort of a snob appeal to this machine.”
“Next year we may have it free for you, we’re campaigning for that. But don’t worry, it’s only a slight improvement over our regular 2D,” the founder of Bon Secours Virginia Breast Center added. Since 2013, the FDA has concluded that a low-dose 3D digital mammography is at least as accurate as 2D mammography. When Bon Secours gets its machine, they can also get 2D digital images from its 3D mammography data.
The 3D works in the same way as 2D, with the woman’s breast pressed between two plates for about six seconds and the camera scanning the breast. The only difference is (and this can be huge) the 2D takes images only from the front and side of the breast, while the 3D is able to take images on each of the inner layers, somewhat like detecting a spot in between pages of a book.
Essentially, abnormalities that may otherwise have been overlooked have a better chance with the 3D. This is enormously valuable for women with dense breasts.
What Do Studies Say on 3D Mammography?
Before the FDA approved 3D, pilot studies found that a combination of 2D plus 3D was more accurate than 2D digital or film mammograms, although the difference in accuracy was tiny for each patient. In addition, women who undergo screening with 3D+2D mammography are less likely to be called back for more testing due to a suspicious finding that turns out not to be cancer.
This means fewer false alarms caused by inaccurate findings.
Of course, using two tests is not practical and exposes women to more radiation. An article published in 2017 in the prestigious medical journal JAMA examined the benefits of 3D mammograms. The study compared the number of callbacks and the numbers of cancers diagnosed before the next scheduled screening in women who had 3D mammograms vs. standard 2D mammograms.
For the more than 23,000 women undergoing an initial 2D mammogram followed by three years of annual 3D mammograms, the use of 3D tests slightly reduced the number of women who got called back (10% in the 2D group vs. 9% in the 3D group) and the number of cancers detected in the months between the annual mammograms.
Following 2D mammography, about seven out of 10,000 women were diagnosed with cancer before their next annual mammography compared to five out of the 10,000 women who underwent 3D mammography screening. While the differences are small, they are statistically significant, which means they did not happen by chance.
Even though the differences are small, 3D tests seem to have a small advantage over 2D tests because they are slightly better at finding dangerous cancers, reducing the number of repeat tests, and reducing the amount of time a woman has to wait to find out.
And what about radiation exposure? “Well, with the 3D, you are slightly longer time under the plate. But the 3D actually and counter-intuitively exposes you to less radiation than the 2D.”
That’s making a clean breast of my clinical history and possibly my age. So to keep abreast of the situation, 3D mammography is slightly better at detecting cancer, but it is not clear how much that benefits the average woman. In all cases, we have to bare our breasts. As breast cancer awareness products say, “Boobs: They Need Your Support!” Or put even more simply, “Save the Boobies.”[su_spoiler title=”Draft recommendations on screening mammography continue to stir debate” style=”fancy” icon=”plus-circle”]Gregory Curfman, MD Assistant Professor of Medicine
Former Editor-in-Chief, Harvard Health Publishing
The release of new guidelines on mammography never fails to renew the heated controversy over the potential benefits and harms of this procedure. The latest draft guidelines from the U.S. Preventive Services Task Force (USPSTF) are no exception. Various expert bodies have already taken conflicting positions on them. You can have your say, too, if you hurry — public comment on the draft closes today.
Screening mammography is done in healthy women to spot hidden breast cancer. Some expert groups say that women should begin having regular mammograms at age 40, others set the start age at 50. The age at which women should stop having mammograms is also disputed.
The USPSTF is an independent panel of experts in primary care and prevention. It is charged with making recommendations on the use of preventive services. Its last recommendations on mammography, made in 2009, said that women between the ages of 50 and 74 should have the test every other year.
The new draft recommendations are similar to those issued in 2009, though there are some differences. The starting and ending ages for screening mammograms are the same. The new draft says there isn’t enough evidence to recommend or discourage the use of a new technique called 3-D mammography for screening. The task force also says that there isn’t enough evidence to recommend that women with dense breasts, who are at higher risk of breast cancer, should have an ultrasound or MRI in addition to screening mammography.
The American Cancer Society and other medical organizations recommend that women begin getting regular mammograms at age 40. The USPSTF, in contrast, advises women between the ages of 40 and 49 to talk with their doctors to make their own decisions about screening depending on how they value the potential benefits and harms of mammography.
Many women, and their doctors, don’t think much about the possible downsides of screening mammography. A statistical model included in the USPSTF draft shows that annual mammograms among 1,000 women in their 40s would prevent one death compared to 1,000 women of the same ages who didn’t have mammograms (7 vs. 8). But screening in this age group would also trigger 576 false positive tests, 58 unnecessary breast biopsies, and two extra over-diagnosed tumors (20 vs. 18) that would not have affected health or longevity.
A study recently released in the journal Health Affairs estimates that false-positive mammograms and the over-diagnosis of breast tumors costs the U.S. health care system $4 billion per year. This figure is much larger than previous estimates and should be part of the national conversation on the use of screening mammography.
While annual mammograms save lives, there are many false positive scans and a small number of over-diagnosed tumors. Individual women may weigh these numbers differently and make different value judgments in deciding whether to start having mammograms at age 40.
For women ages 75 and older, the USPSTF panel continues to say that there isn’t enough evidence to recommend for or against routine mammograms. Other experts suggest that mammograms make sense for women in this age group who are expected to live 10 or more years, based on their good health.
Comments can be made on the USPSTF draft until 8:00 pm Eastern Time today. A final version of the recommendations is expected to be released in the fall of 2015.[/su_spoiler]