by Dr. Elizabeth Chabner Thompson, MD, MPH, Reviewed by Dr. C.H. Weaver M.D. Medical Editor
Controversy about the value of mammography and different screening guidelines in the news have left many women confused; learn the facts about this important diagnostic tool.
Every woman’s health profile is unique—a complex story of age, family history, genetics, lifestyle, and various other factors that combine to create a very individual picture. Breast cancer risk is similarly unique: though on average one in eight women will develop the disease, this is only an average. An individual herself may have a much higher or lower risk.
Adding complexity to this issue of overall risk are conflicting recommendations for when to begin breast cancer screening. The US Preventive Services Task Force recommends beginning screening mammograms in asymptomatic women at age 50, whereas the American Cancer Society recommends beginning at age 40.
Ultimately, early detection saves lives. Finding an early cancer or pre-cancer dramatically increases survival rates. Smaller tumors are easier to treat and afford patients more treatment options. Catching a cancer early also decreases the likelihood that the cancer would have metastasized (spread).
Everyone should consider their unique medical history and consult with their personal physician. At the most basic level, we can consider screening in two phases. First, in your twenties and thirties, perform a breast self-exam at home every month, and be sure to get a clinical breast exam as part of your annual physical. Become familiar with your breasts—the normal shape and contours—so that you can recognize what is new and different. If you notice something that does not seem right, even if you have just seen the physician, make a follow-up appointment.
Second, unless it is recommended earlier, once you hit age 40, begin receiving mammograms every one to two years at the radiologist’s office while continuing to perform self-exams and receive clinical exams at your annual visit with your primary care provider.
Understand the Diagnostic Technology
With new technology coming out every day, it is important to have a basic understanding of the different diagnostic tests available so that you can not only know the right questions to ask but understand the answers and what to ask next.
- Standard 2D mammography has been around since the institution of modern mammography in 1969. It finds calcifications and cancers of the breast 5 millimeters or larger. For some women, such as those with breast implants, additional pictures may be needed and their mammograms need to be done by technicians skilled in techniques used for women with implants.
- Digital mammography, also known as full-field digital mammogram, is fed into a computer so that it can be seen, shared, and stored digitally. The doctor can adjust the image size, brightness, and contrast to see areas more clearly. Digital images can also be sent electronically for consultation.
- 3D Mammograms - Tomosynthesis turns digital mammograms into an image similar to those of magnetic resonance imaging (MRI), which can detect cancers at a smaller size and an earlier stage. The pictures are combined into a 3D image that allows doctors to see problem areas more clearly. This approach will be the standard of care in a few years and is now available at cutting-edge medical centers.
- Doctors may use ultrasound to follow up a suspicious finding on a mammogram or for women with dense, cystic breasts. New technology combines tomosynthesis and ultrasound to make detection of small cancers much easier.
- For certain women at high risk, an MRI is recommended along with, or alternating with, a mammogram. MRI is not generally recommended as a screening tool by itself because, although it is a sensitive test, it may still miss some calcification that mammograms would detect. MRI may also be used in other situations, such as to better examine suspicious areas found by a mammogram.
Check with your insurance company before having a test to find out what it covers. It can help to go to a center with a high-risk clinic, where the staff can assist you in getting approval for a breast MRI.
Know What Your Doctor Is Looking For
Mammograms fall into two categories: screening mammograms, which are used to look for breast disease in women, usually 40 years or older who are asymptomatic, with no breast problems, and diagnostic mammograms, which take more than two views in addition to magnification views. The diagnostic test is used to diagnose breast disease in women who have breast symptoms or an abnormal result on a screening mammogram.
Here are some of the changes that the doctor will look for when reading your mammogram.
- Calcifications are tiny mineral deposits within the breast tissue that appear as small white spots on the films. They may or may not be caused by cancer. There are two types of calcifications:
o Microcalcifications are tiny specks of calcium in the breast. They may appear alone or in clusters. Microcalcifications do not always mean that cancer is present or even that a biopsy (removal and examination under the microscope) is needed. The shape and the layout of microcalcifications help the radiologist judge how likely it is that cancer is present. If the microcalcifications look suspicious for cancer, a biopsy will be performed.
- A cyst is a fluid-filled sac that may be seen on a mammogram. Most cysts are benign, simple cysts that are not cancerous. Other cysts may contain cells within fluid-filled sacs; these are called complex cysts, which are often malignant (cancerous).
- A breast mass (also called a growth or tumor) is an area that looks abnormal on a mammogram. Masses that are totally composed of cells are called solid tumors. Masses can be benign, such as a fibroadenoma, or malignant.
Often it is difficult to tell the difference between a solid tumor mass and a cyst on physical exam or even a mammogram. An additional test called a breast ultrasound can help determine if an abnormality is a solid tumor mass, simple cyst, or complex cyst. A further test or biopsy may be necessary to decide if the mass or cyst is benign or malignant. The physician might use a needle to aspirate (withdraw) fluid from a cyst and examine the fluid microscopically for evidence of malignant cells.
Having your previous mammograms available for the radiologist is very important to help show if a mass or calcification has not changed for many years. Your mammogram report may also contain an assessment of breast density, based on how much of your breast is made up fatty tissue versus fibrous and glandular tissue.
Dense breasts are not abnormal—about half of women have dense breasts on a mammogram. Although dense breast tissue can make it harder to find cancers on a mammogram, at this time experts do not agree what other tests, if any, should be done in addition to mammograms in women with dense breasts.
Mammography Recommendations and Answers to Frequently Asked Questions
How are Mammograms used?
A mammogram can help find breast cancer at an early stage before physical symptoms develop, and when the cancer is most treatable. Women who have regular mammograms are more likely to have breast cancer detected early, are less likely to need aggressive treatment, and are more likely to be cured of a breast cancer.
Do Mammograms ever miss a cancer?
Mammograms are not perfect and do miss some cancers, and sometimes a woman will need additional tests to find out if something found on a mammogram is or is not cancer. There’s also a small possibility of being diagnosed with a cancer that never would have caused any problems had it not been found during screening.
If I have been treated for breast cancer do I still need to get mammograms?
Patients with a history of breast cancer including DCIS or LCIS who have undergone surgery and/or radiation should see a provider every six to twelve months for a physical and history for five years and then annually. They should continue to undergo annual mammograms of the remaining breast(s). Some higher risk individual also may also need to have an MRI.
When should ultrasound or MRI be used instead of or in addition to mammography?
A Mammogram is the main test doctors use to look for a new breast cancer or recurrence of cancer in the breast and should be done annually. Patients who have a lifetime risk of new breast cancer that is 15 to 20 percent or greater, based on genetic mutations, family history or other factors should undergo annual MRI screening. Ultrasound is often used as a supportive test together with mammography or to evaluate a new finding such as a lump but is not recommended as a breast screening test by itself.
What is a 3D Mammogram?
A 3D mammogram is performed that same way as a “traditional” or 2D mammogram in which the breast is compressed between two plates and an image is taken only from the front and side. This may create images with overlapping breast tissue. A 3D mammogram takes images of the breast in “slices” from many different angles and may identify more abnormalities than 2D mammography.
In 2013 the United States Food and Drug Administration concluded that a low-dose 3D digital mammography is at least as accurate as 2D mammography.
Are 3D Mammograms Better?
Clinical studies have demonstrated that the combination of 3D and 2D mammograms are slightly more accurate than 2D digital or film mammograms. Using both tests however is not practical because it exposes women to more radiation. 3D mammograms appear to be slightly better than 2D for both detecting cancer and reducing the number of false positive test. (4-11)
An article published in 2017 in the medical journal JAMA examined the benefits of 3D mammograms. The study compared the number of call backs and the numbers of cancers diagnosed before the next scheduled screening in women who had 3D mammograms compared to standard 2D mammograms. For the more than 23,000 women undergoing an initial 2D mammogram followed by 3 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 7 out of 10,000 women were diagnosed with cancer before their next annual mammography, compared to 5 out of 10,000 of the women who underwent 3D mammography screening. (11)
Does the 3D Mammogram increase radiation exposure?
The 3D test takes a few seconds longer than 2D digital or film mammography (adding a few seconds of discomfort). The newer, low-dose 3D mammography uses less radiation than a 2D mammography.
Are 3D Mammograms covered by Insurance?
Some insurers do not cover 3D mammograms, and others charge women a surcharge. Medicare began covering 3D mammography in 2015.
On average, 3D mammography is slightly better at detecting cancer, but it is not clear how much that benefits the average woman.
What does the data show about 3D Mammograms?
3D Mammography Proves More Accurate in Breast Cancer Detection
Longer follow-up evaluating digital breast tomosynthesis (DBT), also referred to as 3D mammography, demonstrates its continued effectiveness compared to standard digital mammography (DM) when screening for breast cancer. These results were recently published in JAMA Oncology.
It is well established that survival rates for treatment of early breast cancer are significantly superior to survival rates of breast cancer once it has spread to distant sites in the body. Despite this, controversy exists over optimal screening methods, timing, and patient age so that the benefits of screening are maximized, while the potential harms of screening are minimized.
An area of great concern regarding any type of screening includes the rate of false-positive readings of the screening measures. A false-positive reading refers to a screening result that appears suspicious for cancer, requiring follow-up procedures to determine if cancer exists. If it is a false-positive reading, it means that the final results indicate that suspicious area is benign (non-cancerous).
In regards to mammography, the follow-up for a suspicious result can be an additional mammogram, ultrasound, or other type of imaging of the breast, and/or a biopsy. Follow-up procedures are associated with patient anxiety, increased medical costs for subsequent procedures, pain (particularly for a biopsy), scheduled time out of the day for the procedure, and/or even a scar from the biopsy.
In order to reduce false-positive readings that result in follow-up procedures, it remains imperative that researchers strive to provide screening measures that are as accurate as possible.
DBT has been approved by the United States Food and Drug Administration (FDA) as a screening measure for breast cancer. DBT layers additional images of the breast to DM, creating a 3D-visual image that allows radiologists to have a clearer view of the breast tissue.
Results leading to the approval of its use demonstrated that initial use of DBT decreases false-positive examinations, and increases cancer detection compared with DM. However, the long-term benefits of DBT are still under evaluation.
Switching from DM to DBT is associated with initial costs for the machine, as well as resources to instruct both technicians to use the machine, and radiologists to best read results. To justify these upfront costs, researchers continue to evaluate the use of DBT in the clinical setting.
Researchers from the Perelman School of Medicine at the University of Pennsylvania recently conducted a study to explore the longer-term implications of DBT compared to DM, beyond initial screening results. The study was an analysis of data including nearly 24,000 women over the course of 4 years – from 2010 through 2014.
In 2010, all women were screened with only DM. From 2011 through 2014, women received either 1, 2 or 3 screenings with DBT (depending upon how often they returned for regular screening through those years).
- Recall rates (percentage of patients requiring additional follow-up after screening) was significantly reduced with DBT compared to DM.
- The percentage of patients who were diagnosed with cancer among those recalled was significantly higher for DBT compared to DM (indicating superior accuracy of DBT readings).
- Interval cancers (a diagnosis of cancer within 12 months of screening) were reduced with DBT compared to DM.
The researchers concluded that “Digital breast tomosynthesis screening outcomes are sustainable, with significant recall reduction, increasing cancer cases per recalled patients, and a decline in interval cancers.” These results lend to increasing data indicating the superiority of DBT to standard DM as screening for breast cancer.(12)
What is three-compartment breast (3CB) imaging?
According to Dr. Karen Drukker and colleagues from the University of Chicago three-compartment breast (3CB) imaging. 3CB uses non-contrast dual-energy mammography to determine evaluate the composition of biological tissue composition. It can separate water, lipid, and protein components of a suspicious breast mass which helps determine which lesions are more likely to be cancerous.
The University of Chicago doctors reported the results of 109 women with suspicious breast masses that they evaluated with dual-energy mammography. Biopsy results confirmed that of the 35 masses were invasive cancers and 74 were benign. 3CB images were derived from the mammograms and analyzed along with mammography radiomics, a method that uses artificial intelligence algorithms to analyze features and patterns in images.
Combing 3CB image analysis and mammography radiomics improved the ability to predict cancer in breast masses deemed suspicious by the radiologist.The combined method improved the positive predictive value (PPV) from 32% for visual interpretation alone to 49%, with 36% fewer total biopsies. The 3CB-radiomics method missed one of the 35 cancers, for a 97% sensitivity rate.
According to Dr. Drukker "Because 3CB imaging can be performed with conventional mammography or breast tomosynthesis equipment with minimal changes in workflow and minor modifications, and with only a 10% higher dose, the potential exists for wide application of 3CB imaging in diagnostic breast imaging and perhaps also in screening," the team writes."Our study showed that more investigation into the application of 3CB imaging is warranted, and we have initiated a research study incorporating 3CB imaging into breast tomosynthesis."
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.
Sharpe RE Jr, Venkataraman S, Phillips J, Dialani V, Fein-Zachary VJ, Prakash S, Slanetz PJ, Mehta TS. Increased Cancer Detection Rate and Variations in the Recall Rate Resulting from Implementation of 3D Digital Breast Tomosynthesis into a Population-based Screening Program. Radiology. 2015 Oct 9:142036
Greenberg JS, Javitt MC, Katzen J, Michael S, Holland AE. Clinical performance metrics of 3D digital breast tomosynthesis compared with 2D digital mammography for breast cancer screening in community practice. AJR Am J Roentgenol 2014;203(3):687–693.
Friedewald SM, Rafferty EA, Rose SL, et al. Breast cancer screening using tomosynthesis in combination with digital mammography. JAMA 2014;311(24):2499–2507.
Lei J, Yang P, Zhang L, Wang Y, Yang K. Diagnostic accuracy of digital breast tomosynthesis versus digital mammography for benign and malignant lesions in breasts: a meta-analysis. Eur Radiol 2014;24(3):595–602.
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.
McDonald, E., Oustimov, A., Weinstein, S., et al. (2016). Effectiveness of Digital Breast Tomosynthesis Compared With Digital Mammography. Journal of the American Medical Association. Accessed from on June 5, 2018.
McDonald E, Oustimov A, Weinstein S, et al. Effectiveness of Digital Breast Tomosynthesis Compared With Digital Mammography. Outcomes Analysis from 3 Years of Breast Cancer Screening. JAMA Oncol. Published online February 18, 2016. doi:10.1001/jamaoncol.2015.5569.
Elizabeth Chabner Thompson, MD, MPH, is a radiation oncologist, patient advocate, and medical entrepreneur. She earned her medical degree from Johns Hopkins University School of Medicine and her master of public health degree from Harvard University. As founder of BFFL Co, she develops products that improve the patient experience before, during, and after hospitalization in a way that preserves dignity and enhances recovery, including the Elizabeth Pink Surgical Bra.® Dr. Thompson is active in the Harvard School of Public Health Leadership Council, Johns Hopkins University Medical School Alumni Council, and Mt. Sinai Dubin Breast Center Advisory Board.*