- The importance of finding breast cancer early
- What are the risk factors for breast cancer?
- Breast cancer risk factors you cannot change
- Lifestyle-related risk factors for breast cancer
- Factors with uncertain, controversial, or unproven effect on breast cancer risk
- Signs and symptoms of breast cancer
- American Cancer Society recommendations for early breast cancer detection in women without breast symptoms
- Magnetic resonance imaging
- Clinical breast exam
- Breast awareness and self-exam
- Other breast cancer screening tests
- Paying for breast cancer screening
- To learn more about breast cancer early detection
- References: Breast cancer early detection
A mammogram is an x-ray of the breast. A diagnostic mammogram is used to diagnose breast disease in women who have breast symptoms or an abnormal result on a screening mammogram. Screening mammograms are used to look for breast disease in women who are asymptomatic; that is, those who appear to have no breast problems. Screening mammograms usually take 2 views (x-ray pictures taken from different angles) of each breast , while diagnostic mammograms may take more views of the breast. Women who are breastfeeding can still get mammograms, although these are probably not quite as accurate because the breast tissue tends to be dense.
For some women, such as those with breast implants (for augmentation or reconstruction after mastectomy), additional pictures may be needed to include as much breast tissue as possible. Breast implants make it harder to see breast tissue on standard mammograms, but additional x-ray pictures with implant displacement and compression views can be used to more completely examine the breast tissue. If you have implants, it is important that you have your mammograms done by someone skilled in the techniques used for women with implants.
Although breast x-rays have been performed for more than 70 years, modern mammography has only existed since 1969. That was the first year x-ray units dedicated to breast imaging were available. Modern mammogram equipment designed for breast x-rays uses very low levels of radiation, usually about a 0.1 to 0.2 rad dose per x-ray (a rad is a measure of radiation dose).
Strict guidelines ensure that mammogram equipment is safe and uses the lowest dose of radiation possible. Many people are concerned about the exposure to x-rays, but the level of radiation used in modern mammograms does not significantly increase the risk for breast cancer.
To put dose into perspective, a woman who receives radiation as a treatment for breast cancer will receive several thousand rads. If she had yearly mammograms beginning at age 40 and continuing until she was 90, she will have received 20 to 40 rads. As another example, flying from New York to California on a commercial jet exposes a woman to roughly the same amount of radiation as one mammogram.
For a mammogram, the breast is compressed between 2 plates to flatten and spread the tissue. Although this may be uncomfortable for a moment, it is necessary to produce a good, readable mammogram. The compression only lasts a few seconds. The entire procedure for a screening mammogram takes about 20 minutes.
The x-ray machine for mammography
The procedure produces a black and white image of the breast tissue either on a large sheet of film or as a digital computer image that is "read," or interpreted, by a radiologist (a doctor trained to interpret images from x-rays, ultrasound, magnetic resonance imaging, and related tests.)
Like a standard mammogram, a digital mammogram (also known as a full-field digital mammogram or FFDM) uses x-rays to produce an image of your breast. The differences are in the way the image is recorded, viewed by the doctor, and stored.
Standard mammograms are recorded on large sheets of photographic film. Digital mammograms are recorded and stored on a computer. After the exam, the doctor can view them on a computer screen and adjust the image size, brightness, or contrast to see certain areas more clearly. Digital images can also be sent electronically to another site for a consultation with breast specialists. While the digital option is not available at all centers, it is becoming more widely available.
Because digital mammograms cost more than standard mammograms, studies are now looking at which form of mammogram will benefit more women in the long run. Some studies have found that women who have FFDM have to return less often for additional imaging tests because of inconclusive areas on the original mammogram. One large study found that FFDM was more accurate in finding cancers in women younger than 50 and in women with dense breast tissue, although the rates of inconclusive results were similar between FFDM and film mammograms. It is important to remember that a standard film mammogram also is effective for these groups of women, and that they should not miss having their regular mammogram if digital mammography is not available.
What the doctor looks for on your mammogram
The doctor reading your mammogram will look for several types of changes:
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 2 types of calcifications:
- Macrocalcifications are coarse (larger) calcium deposits that most likely represent degenerative changes in the breasts, such as aging of the breast arteries, old injuries, or inflammation. These deposits are associated with benign (non-cancerous) conditions and do not require a biopsy. About half the women over the age of 50, and in about 1 in 10 women younger than 50, have macrocalcifications.
- Microcalcifications are tiny specks of calcium in the breast. They may appear alone or in clusters. Microcalcifications seen on a mammogram are of more concern than macrocalcifications, but do not always mean that cancer is present. The shape and layout of microcalcifications help the radiologist judge how likely it is that cancer is present. In most instances, the presence of microcalcifications does not mean a biopsy is needed. If the microcalcifications look suspicious for cancer, a biopsy will be done.
A mass, which may occur with or without calcifications, is another important change seen on a mammogram. Masses are areas that look abnormal and they can be many things, including cysts (non-cancerous, fluid-filled sacs) and non-cancerous solid tumors (such as fibroadenomas).
Cysts can be simple fluid-filled sacs (known as simple cysts) or can be partially solid (known as complex cysts). Simple cysts are benign and don’t need to be biopsied. Any other type of mass (such as a complex cyst or a solid tumor) might need to be biopsied to be sure it isn’t cancer.
- A cyst and a tumor can feel alike on a physical exam. They can also look the same on a mammogram. To confirm that a mass is really a cyst, a breast ultrasound is often done. Another option is to remove (aspirate) the fluid from the cyst with a thin, hollow needle.
- If a mass is not a simple cyst (that is, if it is at least partly solid), then you might need to have more imaging tests. Some masses can be watched with periodic mammograms, while others may need a biopsy. The size, shape, and margins (edges) of the mass help the radiologist to determine if cancer may be present.
Having your previous mammograms available for the radiologist is very important. They can help show that a mass or calcification has not changed for many years. This would mean that it is probably a benign condition and a biopsy is not needed.
Your mammogram report may also contain an assessment of breast density or state that you have dense breasts. Breast density is based on how much of your breast is made up fatty tissue vs. how much is made up of fibrous and glandular tissue.
Dense breasts are not abnormal. 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.
Limitations of mammograms
A mammogram cannot prove that an abnormal area is cancer. To confirm whether cancer is present, a small amount of tissue must be removed and looked at under a microscope. This procedure is called a biopsy. For more information, see the separate American Cancer Society document, For Women Facing a Breast Biopsy.
You should also be aware that mammograms are done to find cancers that can't be felt. If you have a breast lump, you should have it checked by your doctor, who may recommend a biopsy even if your mammogram result is normal.
For some women, such as those with breast implants, additional pictures may be needed. Breast implants make it harder to see breast tissue on standard mammograms, but additional x-ray pictures with implant displacement and compression views can be used to more completely examine the breast tissue.
Mammograms are not perfect at finding breast cancer. They do not work as well in women with dense breasts, since dense breasts can hide a tumor. Dense breasts are more common in younger women, pregnant women, and women who are breastfeeding, but any woman can have dense breasts.
This can be a problem for young women who are at high risk for breast cancer (because of gene mutations, a strong family history of breast cancer, or other factors) because they have a higher risk of developing breast cancer at a younger age. This is one of the reasons that the American Cancer Society recommends MRI scans in addition to mammograms for screening in these women.
At this time, American Cancer Society guidelines do not contain recommendations for additional testing to screen women with dense breasts who aren’t at high risk of breast cancer.
For more information about mammograms, also see the separate American Cancer Society document, Mammograms and Other Breast Imaging Procedures.
Tips for having a mammogram
The following are useful suggestions for making sure that you receive a quality mammogram:
- If it is not posted in a place you can see it near the receptionist's desk, ask to see the FDA certificate that is issued to all facilities that offer mammography. The FDA requires that all facilities meet high professional standards of safety and quality in order to be a provider of mammography services. A facility may not provide mammography without certification.
- Use a facility that either specializes in mammography or does many mammograms a day.
- If you are satisfied that the facility is of high quality, continue to go there on a regular basis so that your mammograms can be compared from year to year.
- If you are going to a facility for the first time, bring a list of the places, dates of mammograms, biopsies, or other breast treatments you have had before.
- If you have had mammograms at another facility, you should make every attempt to get those mammograms to bring with you to the new facility (or have them sent there) so that they can be compared to the new ones.
- Try to schedule your mammogram at a time of the month when your breasts are not tender or swollen to help reduce discomfort and assure a good picture. Try to avoid the week right before your period.
- On the day of the exam, don't wear deodorant or antiperspirant. Some of these contain substances that can interfere with the reading of the mammogram by appearing on the x-ray film as white spots.
- You may find it easier to wear a skirt or pants, so that you'll only need to remove your blouse for the exam.
- Schedule your mammogram when your breasts are not tender or swollen to help reduce discomfort and to ensure a good picture. Try to avoid the week just before your period.
- Always describe any breast symptoms or problems that you are having to the technologist who is doing the mammogram. Be prepared to describe any medical history that could affect your breast cancer risk—such as prior surgery, hormone use, or family or personal history of breast cancer. Also discuss any new findings or problems in your breasts with your doctor or nurse before having a mammogram.
- If you do not hear from your doctor within 10 days, do not assume that your mammogram result was normal. Call your doctor or the facility.
What to expect when you get a mammogram
- Having a mammogram requires that you undress above the waist. The facility will give you a wrap to wear.
- A technologist will be there to position your breasts for the mammogram. Most technologists are women. You and the technologist are the only ones in the room during the mammogram.
- To get a high-quality mammogram picture, it is necessary to flatten the breast slightly. The technologist places the breast on the mammogram machine's lower plate, which is made of metal and has a drawer to hold the x-ray film or the camera to produce a digital image. The upper plate, made of plastic, is lowered to compress the breast for a few seconds while the picture is taken.
- The whole procedure takes about 20 minutes. The actual breast compression only lasts a few seconds.
- You may feel some discomfort when your breasts are compressed, and for some women compression can be painful. Try not to schedule a mammogram when your breasts are likely to be tender, as they may be just before or during your period.
- All mammogram facilities are now required to send your results to you within 30 days. Generally, you will be contacted within 5 working days if there is a problem with the mammogram.
- Being called back for more testing does not mean that you have cancer. In fact, less than 10% of women who are called back for more tests are found to have breast cancer. Being called back occurs fairly often, and it usually just means an additional image or an ultrasound needs to be done to look at an area more clearly. This is more common for first mammograms (or when there is no previous mammogram to look at) and in mammograms done in women before menopause. It may be slightly less common for digital mammograms.
- Only 2 to 4 screening mammograms of every 1,000 lead to a diagnosis of cancer.
If you are a woman and age 40 or over, you should get a mammogram every year. You can schedule the next one while you're there at the facility. Or, you can ask for a reminder to schedule it as the date gets closer.
For more information on mammograms and other imaging tests for early detection and diagnosis of breast diseases, refer to the American Cancer Society document, Mammograms and Other Breast Imaging Procedures.
Last Medical Review: 08/30/2012
Last Revised: 02/06/2013