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Mammograms are an important screening test to ease your mind from year to year, starting around age 40 for most women, to know your breast cancer status. They are one tool in the breast cancer diagnosis tool kit. Mammograms can sometimes detect breast cancer in the earliest stages, before any symptoms are present and early detection leads to better outcomes.
This article will explain what to expect during a mammogram, what types of tests are available, and the importance of keeping up with your annual health checks.
what to expect during a mammogram
Purpose of Test
A mammogram may be ordered as a screening test to look for any evidence of breast cancer in people who may or may not have any symptoms.
Different organizations, including the American Cancer Society, the U.S. Preventive Services Task Force, and the American College of Obstetricians and Gynecologists have somewhat different breast cancer screening guidelines.1
These recommendations are intended for women at average risk only. Those at increased risk may require earlier or more frequent mammograms or other screening tests, such as magnetic resonance imaging (MRI).
Risk Factors for Breast Cancer
A mammogram may also be done as a diagnostic test for those who have any signs or symptoms of breast cancer, such as:2
A breast lump or lump in the armpit (axillary mass)
Thickening or swelling of a breast or part of a breast
Dimpling of the breast skin
A change in the size or shape of the breast
A sense of heaviness in one breast
Nipple retraction (pulling in of a nipple)
Nipple discharge
Breast pain
Redness, scaling, a rash, or irritation of the breast or nipples
Itchy breasts
Male Breast Cancer
A mammogram may be recommended for men who carry the BRCA1, BRCA2, or PALB genes. Male breast cancer is much less common than breast cancer in women, but it does occur.3
Fast MRI for Breast Cancer Screening
Limitations
A mammogram has limitations in returning accurate results. Despite being highly valuable, mammograms can vary in their sensitivity (the ability to correctly identify people with the disease) and specificity (the ability to correctly identify people without the disease). The sensitivity and specificity can be influenced by numerous factors, occasionally leading to incorrect, or false, diagnoses.4
False Negatives
A mammogram may not detect the presence of breast cancer when it is there. This is referred to as a false-negative result.
Women must be informed if they have dense breasts and may consider the option of additional screening, such as breast ultrasound or fast breast MRI (magnetic resonance imaging).
In early studies, fast breast MRI better detects breast cancer (especially more aggressive breast cancers) with fewer positives (incorrectly indicates breast cancer is present when it is not) than the combination of mammography and ultrasound. Some studies suggest that fast MRI may be comparable to conventional MRI, which is the screening method of choice for women who are high risk.5
Breast cancers such as inflammatory breast cancer and Paget's disease of the breast are less likely than other types to be seen on a screening mammogram.6 In addition, most women who have inflammatory breast cancer also have dense breasts, which further reduces the chance of spotting these cancers.7
Why Mammograms Are Done Before Ultrasounds
False Positives
Mammograms may also raise concern over harmless breast changes, particularly with regards to benign (noncancerous) breast lesions that can mimic breast cancer. These can lead to false-positive results, which can lead to more invasive testing and unnecessary treatment.
False-positive results are more common in younger women who have dense breasts, for those who have had previous surgery on their breast (such as a breast biopsy), for those who are using hormonal therapy, and for those who have risk factors for breast cancer.4
Having a baseline mammogram available to compare with has been found to significantly reduce the chance of getting a false-positive result. A baseline mammogram usually is a person’s first mammogram.
For women who have breast implants, images may not be as accurate without special views, as X-rays don't travel well through either saline or silicone, the materials used to fill implants. With special views (two for each breast) however, the accuracy is greatly improved.
False-Positive Results
More than 50% of women who are screened every year for 10 years in the United States will likely get a false-positive result, according to the National Cancer Institute.8
It is important to remember that mammograms cannot diagnose breast cancer but can only reveal suspicious findings. A breast biopsy (removing a sample of tissue for examination in a lab) would be needed to make a definitive diagnosis.
How Breast Cancer Is Diagnosed
Similar Tests
You may hear a distinction between conventional mammography and digital mammography, which is most commonly used in the United States. The difference between the two is that conventional mammography is stored on film, whereas digital mammography is stored on solid state detectors.
Digital mammograms have the advantage of being able to be moved and magnified during readings and can be transferred electronically. They are also more accurate in women with dense breasts and involve less radiation.
That said, digital mammography is usually more expensive than conventional mammography, and in some areas of the world, only conventional mammography may be available.
There are other forms of mammography that are now available or being evaluated in studies. Digital breast tomosynthesis (DBT), better known as 3D mammography, is similar to a computed tomography (CT) scan that uses multiple X-ray slices to create a three-dimensional image of the breast. It involves slightly more radiation than digital mammography, and it's not known yet know if there are any significant advantages of this technology. Optical mammography is also being evaluated for accuracy, but more studies need to be done before recommending this option.9
Other tests that complement mammograms include elastography. This is a test that looks at the elasticity of the breast. It's currently used to determine if a biopsy is needed on a mass that is found.
Why Not Annual Ultrasounds Instead of Mammograms?
Complementary Tests
A number of different tests may be ordered along with a mammogram. If you find a lump, or if there is suspicion of a lump on a mammogram, a breast ultrasound may also be done. A breast ultrasound can help differentiate a cystic mass (breast cyst) from a solid mass.
Women who have an increased risk of developing breast cancer or women who have dense breasts may benefit from additional screenings, such as combining a breast MRI with mammography.10
Risks and Contraindications
Mammograms expose women to a small amount of radiation, the amount of which rarely causes illness.
According to a 2016 study in the Annals of Internal Medicine, an estimated 125 of every 100,000 women who undergo an annual mammogram will develop radiation-induced breast cancer, of whom 16 (or 0.00016 percent) will die.11
(By comparison, among the same group of women, 968 breast cancer deaths could be avoided as a result of the mammograms.)
The risk of radiation from mammograms is expected to be higher in those who receive higher doses of radiation and in women who have larger breasts, as they require additional radiation to accurately view all breast tissue.
For women who have breast implants, there is a small risk that an implant could rupture, and it's important to let the technician know you have implants before the procedure.11
Before the Test
Before you have your mammogram, your healthcare provider will ask you about any risk factors you have, as well as any symptoms of breast cancer.
Timing
Though the mammogram itself usually takes around 10–15 minutes to complete, plan on spending at least an hour at your appointment to check in and give your radiologist time to review your images.
Location
There are many places where a mammogram can be conducted, including outpatient clinics, hospitals, and even mobile mammography units.
What to Wear
You will be asked to change into a gown before your mammogram. Since you will only need to remove clothing from above your waist, wearing a two-piece outfit can make this process faster and easier.
Leave the Deodorant at Home
Many personal care products contain metallic particles (such as aluminum) that can interfere with the images obtained (particles may look like calcifications).
Cost and Health Insurance
Most health insurance plans cover screening mammograms, as well as mammograms that are done to evaluate symptoms. The average cost for a mammogram is around $100 but can vary by location and whether any special views are ordered.
For those who do not have insurance, there are a number of state and local programs that provide free or low-cost mammograms, and some employers also offer discounted mammograms. The National Breast and Cervical Cancer Early Detection Program, a program of the Centers for Disease Control and Prevention (CDC), also offers free or low-cost mammograms to women who need financial help.12
If you are unable to find free or low-cost mammograms in your area, you may receive a discount if you let the clinic know that you do not have insurance.
Where to Find Low-Cost or Free Mammograms
What to Bring
If you had previous mammograms at another facility, you may be asked to bring your films to your appointment. Radiologists usually want an actual copy of the scan (most departments can burn a CD of your scan that you can take with you) rather than a written report.
Reducing Pain
Some women can find mammograms uncomfortable.13 You can do the following ahead of time to make your mammogram less painful:
Schedule your mammogram 10 days after your period. Hormone levels fluctuate during the menstrual cycle, and your breasts are likely to be the least tender and swollen at this point.
Use an anti-inflammatory medication such as Advil (ibuprofen) or Aleve (naproxen) one hour prior to the test.
Avoid caffeine during the week prior to your mammogram
During the Test
When you are ready for your test, a radiology technician will take you back into the mammogram suite. You may or may not see the radiologist who will review your images.
Pre-Test
Many clinics will have you complete a questionnaire before you have your mammogram. These forms usually ask about any risk factors you have for breast cancer, any symptoms you are having, and any previous history of abnormal mammograms, breast biopsies, or breast surgery.
You may also have markers placed on your breast. These are used for a number of different reasons, such as to mark nipples, moles, scars, and any lumps or areas of pain you have noticed.
Throughout the Test
The test is usually performed while you are standing. The machine has handles you can grasp to help you remain still while the images are taken. For those who are unable to stand, sitting mammography may also be done.
When the test begins, your technician will help you place your breast between two plates. These plates are then compressed, squeezing your breast as the images are taken. You will be asked to take a deep breath and hold it for a few seconds to ensure a clear reading. Compression allows more tissue to be seen with less radiation, helps reduce blurring along the edges of the film, and allows X-rays to pass through the tissue more easily.9
If you experience any discomfort, let the technician know. In some cases, your breast can be repositioned without compromising the image. Even so, each image usually takes only a minute or less to complete.
In a standard screening mammogram, two mammogram views are taken on each breast: one craniocaudal (a view of your breasts from above) and the other mediolateral-oblique (a view of your breasts from the center outwards). The mediolateral-oblique view captures more breast tissue and allows better visualization of the upper chest and armpit.
Additional views, such as spot compression, cleavage view, and others may be done if needed to get an accurate image of your breasts. If you have breast implants, you may need special implant displacement views completed.9
After the Test
When your mammogram is completed, you may be asked to wait until the radiologist reviews your images. A report will be sent to your healthcare provider who will notify you of your results.
The discomfort of breast compression often improves rapidly when the test is done, but some women continue to feel aching in their breasts for a day or two after the test.13 If you do feel uncomfortable, wear a comfortable sports bra or camisole under your clothes.
Interpreting Results
After your mammogram, a radiologist will review your images and compare these with any previous mammograms you have had. The time it takes until your results are available can vary, and, with some clinics, it may take up to a month before a written report is sent to you.
Your mammogram report will include the following information:14
Patient information
Medical history
Procedures (such as previous biopsies)
Findings
Impression (referred to as a Breast Imaging Reporting and Data System, or BIRADS, classification)
Recommendation for further tests, if needed
It is extremely important to contact your healthcare provider if you have not received your results. Don't assume that all is fine if you haven't heard anything.
Findings
The findings section may simply say that your test was normal, negative, or benign. But if your radiologist sees anything that is suspicious or suggestive of malignancy, the report will describe the size of the finding, the location, and the shape or outline of the abnormal region.
There are a number of terms that may be used to describe findings, including:
Clustered breast calcifications or microcalcifications (calcifications appear as white spots on a mammogram, and their significance can vary)
A spiculated mass (a lump that has spikey borders like a starfish)
An asymmetrical density of breast tissue
Skin thickening
Retraction (areas of skin or nipple pulling inward)
Focal distortion (something is pressing on tissue)
In all cases, the report may also include a description of the density of your breast tissue.15
Normal and Abnormal Mammogram Images
BIRADS Classification
Your mammogram report will include a Breast Imaging Reporting and Data System number—the BIRADS classification—which is a number used to indicate your radiologist’s overall impression of your mammogram. This scale was developed to help standardize mammograms done across the country and at different institutions.
The scale for BIRADS goes from zero to five, with higher numbers indicating a greater possibility of breast cancer:
0: The mammogram report is incomplete, and an impression cannot be given until further views are done, other tests (such as an ultrasound) are performed, or the mammogram is compared with previous films.
1: Negative
2: Benign findings, such as benign calcifications or a benign fibroadenoma
3: Probably benign, with a 98% chance that it is not cancer. This usually means you will need earlier follow-up, such as a mammogram in six months.
4: Suspicious abnormality; a biopsy is often indicated. This can be broken down into 4A, 4B, and 4C, with 4A meaning a lower chance that it is cancer, and 4C indicating a higher chance of the disease.
5: Highly suggestive of malignancy; a biopsy should be done. Radiologists give a score of 5 when they estimate the chance that the findings mean cancer is 95% or higher.15
A BIRADS score of 6, meaning cancer, can only be made with a breast biopsy.
Follow-Up
Your radiologist may make some recommendations based on your mammogram results. In some cases, no other studies may be needed. But if so, they may include:
Follow-up imaging
Spot views
Magnification
Diagnostic mammogram
Breast ultrasound for lumps and masses: This test can often distinguish between solid masses and breast cysts, which you may get the same day as your mammogram.
Breast MRI: There are several differences between a mammogram and an MRI in the evaluation of breast tissue, and an MRI may be more accurate for those who have a family history, other risk factors, or dense breasts.
Breast biopsy: This conclusively diagnoses or rules out breast cancer.
If your mammogram is normal, and you have no symptoms of breast cancer, it's important to continue to follow breast screening guidelines.
If any abnormalities are found, or if the mammogram is difficult to interpret, talk to your healthcare provider. The radiologist will be able to review your images, but your healthcare provider can also look at your risk factors, findings on physical exam, and your medical and family history, to help guide you as to your next steps.