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A mammogram is an X-ray of the breast that is used to screen for breast cancer. Mammograms can find tumours that are too small for you or your doctor to feel.
There are several types of mammograms. They include:
- Standard mammogram. It puts images of the breast on film.
- Digital mammogram. It puts images of the breast into an electronic file. This allows your doctor to see different views of the breast without taking more images.
- Digital breast tomosynthesis is sometimes called 3D mammogram. It uses X-rays to create a three-dimensional image of the breast. This test may be used alone or with a digital mammogram.
Cancer is most easily treated when it's discovered in an early stage. Mammograms don't prevent breast cancer or reduce your risk of developing cancer. But from ages 40 to 70, mammograms may help reduce deaths from breast cancer.
Your doctor may recommend testing at a younger age if you have risk factors for breast cancer.
A mammogram can seem to detect a cancer, when in fact there's no cancer there. This is called a false-positive result. It can occur at any age, but it's more likely to occur if you are age 40 to 59. About 5% to 10% of screening mammograms will require more testing. This may include another mammogram of specific breast tissue or another test, such as an ultrasound. Most of these tests will show that no cancer is present.
Why It Is Done
A mammogram is done to:
- Look for breast cancer when there are no symptoms.
- Find breast cancer when there are symptoms. Symptoms of breast cancer may include a lump or thickening in the breast, nipple discharge, or dimpling of the skin on one area of the breast.
- Find an area of suspicious breast tissue to remove for an examination under a microscope (biopsy).
How To Prepare
If you've had a mammogram before at another clinic, have the results sent or bring them with you to your appointment.
On the day of the mammogram, don't use any deodorant. And don't use perfume, powders, or ointments near or on your breasts. The residue left on your skin by these substances may interfere with the X-rays.
How It Is Done
You will need to remove any jewellery that might interfere with the X-ray picture. You will need to take off your clothes above the waist, and you will be given a cloth or paper gown to use during the test.
For a standard or digital mammogram, you'll probably stand during the test. One at a time, your breasts will be placed on a flat plate. Another plate is then pressed firmly against your breast to help flatten out the breast tissue. Very firm compression is needed to obtain high-quality pictures. You may be asked to lift your arm. For a few seconds while the X-ray picture is being taken, you will need to hold your breath. Usually at least two pictures are taken of each breast: one from the top and one from the side.
For a 3-D mammogram, you will also stand, and your breast will be positioned on a flat plate. The top plate is pressed against your breast with just enough pressure to keep the breast in position while the X-ray arm moves in an arc above the breast. Many images are taken in a very short time. A computer is used to combine these images to create a 3-dimensional picture of the breast.
How long the test takes
- The test will take about 10 to 15 minutes. You may be in the clinic for up to an hour.
- You may be asked to wait a few minutes while the images are checked to make sure they don't need to be redone.
How It Feels
A mammogram is often uncomfortable but rarely painful. If you have sensitive or fragile skin or a skin condition, let the technician know before you have your examination. If you have menstrual periods, the procedure is more comfortable when done within 2 weeks after your period has ended.
Having your breasts flattened is usually uncomfortable, but it helps the technician get the best images.
A mammogram may help find cancer early. But finding cancer early doesn't always save lives. In some cases the cancer will have already spread to other parts of the body.
A mammogram may appear to detect a cancer even when there's no cancer there (false-positive results). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. False-positive results can lead to emotional distress and unneeded tests and treatments.
A mammogram may miss finding breast cancer even when it is there (false-negative results). This is more likely to happen if the breast tissue is dense. False-negative results can keep you from getting treatment and can give a false sense of security.
Also, mammograms may find certain types of breast cancer that would never cause symptoms or be life-threatening. But doctors can't tell what kinds of cancer will cause problems, so all cancers are treated. This means that you could end up having tests and treatments that you don't need. These can cause harm.
There is a risk of damage to cells or tissue from being exposed to radiation, including the small amounts used in CTs, X-rays, and other medical tests. Over time, exposure to radiation may cause cancer and other health problems. But in most cases, the risk of getting cancer from being exposed to small amounts of radiation is low. It's not a reason to avoid these tests for most people.
Mammogram results are usually ready within 10 days. In some cases, you may be asked to come back for another test to get an extra view of an area in question.
The results of a screening mammogram are sent directly to your family doctor's office. And in some provinces, they also will be sent directly to you. If the mammogram is done to diagnose a problem, the results will be sent to your family doctor, and he or she will discuss the results with you.
Breast tissue looks normal. No unusual growths, lumps, or other types of abnormal tissue are seen. The glands that produce milk for breastfeeding and the tubes (ducts) through which milk flows appear normal.
An abnormal growth, lump, or other type of tissue may be seen. A cancerous (malignant) or non-cancerous (benign) tumour may be seen. One or more fluid-filled pockets (cysts) may be seen.
Bits of calcium (calcifications) may be seen. Tiny calcifications (microcalcifications) often occur in areas where cells are growing very rapidly (such as in a cancerous tumour). Larger calcifications (macrocalcifications) are usually normal and non-cancerous in people older than age 50.
Need more information:
A specific area needs to be looked at again. This is a very common result and doesn't mean that the area is abnormal or cancerous.
Most abnormalities found during a mammogram aren't breast cancer. But it's common to need more tests to be sure. If an area of your breast tissue appears to be a concern during a mammogram, other tests may be done.
Current as of: August 2, 2022
Author: Healthwise Staff
Medical Review:Kathleen Romito MD - Family Medicine & Kirtly Jones MD - Obstetrics and Gynecology