A Mammography Guide

Should I “Upgrade” to Digital or 3D? A Mammography Guide

By Susan Dudley, PhD, and Caitlin Kennedy, PhD

Updated November 2013

Every year over 200,000 women in the U.S. are diagnosed with breast cancer, and every year breast cancer that has spread from the breast to other parts of the body (“late stage” or “metastatic” breast cancer) kills about 40,000 women.¹ When breast cancer is detected early—before it has spread—it is easier to treat and women have a much better chance of becoming “breast cancer survivors.” For now, mammograms are the best way of screening women for breast cancer. To find out when to begin mammograms and how often to get them, read our 2012 update, When Should Women Start Regular Mammograms? 40? 50? And How Often is “Regular”?

Forty million mammograms are performed each year,² but the technology is evolving. Depending on where a woman lives, she may be able to choose from among three different types of mammography. Does it matter what kind of mammogram she gets?

Digital vs. Film Mammography

Most Americans are familiar with the differences between digital cameras and their older, film-based predecessors. Similar digital technologies are now also available for mammography. Is this an important advance for women’s health care that women should request, or are the “old fashioned” film images just as good and less expensive?

To answer these questions, 2D digital and film mammography were directly compared in a large study published in the New England Journal of Medicine in 2005.³ Nearly 50,000 women in the study had both types of mammogram performed. The researchers found that for most women, the two methods are equivalent. Three smaller, earlier studies had arrived at this same conclusion,^4, 5, 6 and in 2009, the U.S. Preventative Services Task Force recommendations for breast cancer screening stated that there is not enough evidence of the benefits of digital mammography over film mammography to recommend digital: that 2D digital mammograms were not more accurate at detecting breast cancer than film mammograms.

Risks and Benefits

For most women, there is no reason to choose 2D digital mammography over film since it costs more. However, the study published in the New England Journal of Medicine suggests that for some women 2D digital images might be more accurate:

• those who are younger than 50,
• those who are pre- or peri-menopausal, and
• those who have very dense breasts (dense breasts are more common in women under 50).

In those groups, which often overlap, some cancers were visible on 2D digital images that could not be found on film images.

More recent studies published in 2007, 2008, and 2011 found similar results: 2D digital mammography is more accurate than film for these specific groups of women.^7, 8, 9

For those groups of women where 2D digital mammography is more accurate, does it save lives?   

Many of the abnormalities detected by digital mammography may not be dangerous, and their detection could result in unnecessary anxiety, testing, and treatment. These issues are being considered by experts from across the U.S. in a broader review of whether lesions called Ductal Carcinoma in Situ (DCIS), for example, should be considered cancer or not.¹⁰

From a patient’s perspective, the mammography experience is about the same with 2D digital or film. Nevertheless, some advantages and disadvantages of the two methods have been identified, including:

• A single exposure to radiation is sufficient to produce a film image. With digital images, however, women with large breasts may need to have several additional exposures to get an equivalent image. This disadvantage would not be an issue for women with smaller breasts.
• Digital mammography equipment can cost up to four times what a conventional film-based equipment does, and some of this extra cost is passed on to the patient.
• Because digital mammograms are stored as computer files, copying and retrieval are easier.

 A New Type of Digital Test: 3D Mammography

3D mammograms are currently offered in 48 states and over 50 countries.¹¹ They were originally approved by the FDA only as an add-on to standard film or digital (2D) mammography, but in 2013 the FDA decided that a low-dose 3D digital mammography was accurate enough to be used by itself. 3D mammography provides images of the breast in “slices” from many different angles, whereas 2D mammograms (whether digital or film) make images of the breast from only two angles: from the front and side. In 2D mammograms, the breast is compressed between two plates, which may create images with overlapping tissue. As a result, finding abnormalities may be easier with 3D tests. Also, 2D digital images can be obtained from the 3D mammogram data without the need for a separate test.

Differences between 2D and 3D Mammograms

3D mammograms have been found to correctly identify cancers 4-5% more often than regular 2D digital or film mammograms.^12, 13 Just as importantly, women who undergo screening with 3D mammography are 15% less likely to be called back for more testing due to a suspicious finding that turns out not to be cancer. This is called the “non-cancerous recall rate,” which when lower means fewer false scares.¹⁴

Does this mean that 3D mammography is truly better than 2D for most women? There is no evidence that 3D mammograms have a real health benefit, such as reducing the number of women who die of breast cancer.

Comfort: From a practical point of view, 2D and 3D mammography involve the same amount of physical discomfort.

Cost: 2D digital mammograms are a bit more expensive than traditional film ones and can cost anywhere from $150 to $300.^15, 16 Both types of 2D screening mammograms are covered by most healthcare insurance and will be covered by all under the Affordable Care Act. 3D mammograms, however, are not covered by health insurance—not even under the Affordable Care Act (“Obamacare”).

Radiation exposure: The 3D test takes a few seconds longer than 2D digital or film mammography, and the amount of radiation exposure is about the same for women with small to medium breasts. As with 2D digital mammograms, women with large breasts may need extra pictures, which mean more radiation exposure than from regular film mammograms.

Unnecessary medical procedures: While 3D mammograms may result in fewer unnecessary recalls involving more imaging and more radiation exposure, they can lead to women getting more biopsies and other types of tests for abnormalities that are not dangerous.

Because digital mammography—both 2D and 3D—are relatively new, no one has really figured out what all the financial and emotional risks are or what the added cancer risk is for women with larger breasts who may need additional images and therefore get more exposure to radiation.

The Bottom Line

For women over 50, there is no evidence that digital screening mammograms (whether 3D or 2D) are better for women’s health than traditional film mammograms. For most women, digital mammography (2D and especially 3D, which is not covered by insurance) may be unnecessarily expensive and may detect abnormalities that are not dangerous but will be treated, nevertheless, because they are “there.” When doctors and patients discover abnormalities, even if they present very little risk or an unknown risk in the future, they usually undergo treatment. Unfortunately, unnecessary “over-treatment” has risks.

2D digital mammography may be more accurate for women with dense breasts and women under 50, but most women under 50 do not need screening mammography. See When Should Women Start Regular Mammograms? 40? 50? And How Often is ‘Regular’? for more information.

1. National Cancer Institute. “SEER Stat Fact Sheets: Breast Cancer.” http://seer.cancer.gov/statfacts/html/breast.html (Accessed November 20, 2013).  ▲
2. U.S. Food and Drug Administration. “Radiation-Emitting Products.” http://www.fda.gov/Radiation-EmittingProducts/MammographyQualityStandardsActandProgram/FacilityScorecard/ucm113858.htm (Accessed November 20, 2013).  ▲
3. Pisano ED, Gatsonis C, Hendrick E, et al. Diagnostic Performance of Digital versus Film Mammography for Breast-Cancer Screening. New England Journal of Medicine, 2005; 353(17): 1773-1783.  ▲
4. Cole E, Pisano ED, Brown M, Kuzmiak C, Braeuning MP, Kim HH, Jong R, & Walsh R. Diagnostic accuracy of Fischer Senoscan Digital Mammography versus screen-film mammography in a diagnostic mammography population. Academic Radiology 2004; 11: 879-886. Retrieved from http://www.academicradiology.org/.  ▲
5. Lewin JM, D’Orsi CJ, Hendrick RE, Moss LJ, Isaacs PK, Karellas A, & Cutter GR. Clinical comparison of full-field digital mammography and screen-film mammography for detection of breast cancer. American Journal of Roentgenology 2002; 179: 671-677. doi: 10.2214/ajr.179.3.1790671.  ▲
6. Skaane P, Young K, & Skjennald A. Population-based mammography screening: Comparison of screen-film and full-field digital mammography with soft-copy reading – Oslo I study. Radiology 2003; 229: 877-884. Retrieved from http://pubs.rsna.org.proxy3.library.jhu.edu/journal/radiology.  ▲
7. Rosselli del Turco M, Mantellini P, Ciatto S, Bonardi R, Martinelli F, Lazzari B, Houssami N. Full-field digital versus screen-film mammography: Comparative accuracy in concurrent screening cohorts. American Journal of Roentgenology 2007; 189(4): 860-866. doi: 10.2214/AJR.07.2303.  ▲
8. Pisano ED et al. Diagnostic accuracy of digital versus film mammography: Exploratory analysis of selected population subgroups in DMIST. Radiology 2008; 246(2): 376-383. Retrieved from http://pubs.rsna.org/journal/radiology.  ▲
9. Kerlikowske K, Hubbard RA, Miglioretti DL, Geller BM, Yankaskas BC, Lehman CD, Taplin SH, & Sickles EA. Comparative effectiveness of digital versus film-screen mammography in community practice in the United States. Annals of Internal Medicine 2011; 155: 493-502. Retrieved from http://annals.org/.  ▲
10. Esserman LJ, Thompson IM, & Reid B. Overdiagnosis and overtreatment in cancer: An opportunity for improvement. Journal of the American Medical Association 2013: online version, E1-E2. doi:10.1001/jama.2013.108415.  ▲
11. Yahoo Finance. “Hologic receives FDA approval for low-dose 3D mammography (breast tomosynthesis) solution for breast cancer screening.” http://finance.yahoo.com/news/hologic-receives-fda-approval-low-121500198.html. (Accessed November 7, 2013).  ▲
12. U.S. Food and Drug Administration. “Summary of Safety and Effectiveness Data (SSED): Selenia Dimensions 3D System.” http://www.accessdata.fda.gov/cdrh_docs/pdf8/P080003S001b.pdf (Accessed November 20, 2013).  ▲
13. Rose S, Tidwell AL, Bujnoch LJ, Kushwaha AC, Nordmann AS, & Sexton R. Implementation of breast tomosynthesis in a routine screening practice: An observational study. AJR online; March 22, 2013. doi: 10.2214/AJR.12.9672.  ▲
14. Skaane P, Bandos AI, Gullien R, Eben EB, Ekseth U, Haakenaasen U, Izadi M, Jebsen IN, Jahr G, Krager M, Niklason LT, Hofvind S, & Gur D. Comparison of digital mammography alone and digital mammography plus tomosynthesis in a population-based screening program. Radiology 2005; 267(1): 47-56. doi: 10.1148/radiol.12121373.  ▲
15. Iowa Radiology, email communication, November 2013.  ▲
16. Washington Radiology Associates, email communication, November 2013.  ▲

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• 感谢您的信息，非常有帮助. -Lilac2003- ♀ (0 bytes) () 11/25/2014 postreply 06:43:59