A mammogram is an x-ray of the breast. Diagnostic mammography is used to diagnose breast disease in women who have symptoms such as the changes listed above. Screening mammography is used to look for breast disease in women who are asymptomatic, that is, they appear to have no breast problems.
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. With modern mammography equipment used specifically for breast x-rays, very low levels of radiation are used, usually about 0.1 to 0.2 rad dose per x-ray. Strict guidelines are in place to assure that mammography equipment is safe and uses the lowest dose of radiation possible. Many people are concerned about the exposure to x-rays, and rightly so, but the level of radiation in up-to-date 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 thousands rads. If a woman had yearly mammograms beginning at age 40 years and continuing until 90, she will have received 10 rads. As another example, one mammogram exposes a woman to roughly the same amount of radiation as flying from New York to California on a commercial jet.
In order to perform a mammogram, the breast is compressed to flatten and spread the tissue. Although this may be temporarily uncomfortable, it is necessary in order to produce a good mammogram. The compression only lasts a few seconds, and the entire procedure for screening mammography takes about 20 minutes. This procedure produces a black and white image of the breast tissue on a large sheet of film that is "read," or interpreted, by a radiologist. The physician reading the films will look for several types of changes.
Calcifications, or microcalcifications, are tiny mineral deposits within the breast tissue which appear as small white spots on the film. They may occur singly or in clusters. They are a sign of changes within the breast that can either be monitored by additional, periodic mammograms, or can be examined by biopsy (removal of a small amount of breast tissue). They may be caused by benign breast conditions, or, less often, by breast cancer. Another important change that can be seen on a mammogram is a mass, which may occur with or without calcifications. Masses can be due to many things, including cysts and fibroadenomas, but may be cancer and usually should be biopsied if they are not fluid-filled cysts.
A cyst, which is a benign collection of fluid in the breast, cannot be diagnosed by physical exam alone, nor can it be diagnosed by mammography alone. Either breast ultrasound, or removal of the fluid with a needle (aspiration), is used to confirm that a mass is a cyst. If a mass is not a cyst, then further imaging may be obtained.
As with calcifications, a mass can be caused by benign breast conditions, or by breast cancer. Some masses can be monitored with periodic mammograms, while others may require immediate or delayed biopsy.
A mammogram, while suggestive, cannot prove that an abnormal area is cancer. To confirm whether cancer is present, a small amount of tissue must be removed and examined under a microscope. This procedure is called a biopsy. For more information refer to the American Cancer Society document on "Mammography and Other Breast Imaging Procedures."
8 Things to Expect When You Get a Mammogram
- Mammogram costs, or a percentage of them, are covered by Medicare, Medicaid, and most private health plans. Low cost mammograms are available in most communities. Call the American Cancer Society at 1-800-ACS-2345 for information about facilities in your area.
- The procedure requires that you undress above the waist. A wrap will be provided by the facility for you to wear.
- A technologist will be present to position your breasts for the mammogram. Most technologists are women. You and the technologist are the only ones present during the mammogram.
- The procedure takes about 20 minutes. The actual breast compression only lasts a few seconds.
- You may feel some discomfort when your breasts are compressed, but you should not feel pain. To help lessen discomfort, don't have a mammogram just before or during your menstrual period. If you experience pain during the mammogram, tell the technologist.
- All mammography facilities are now required to send your results to you within 30 days. You will be contacted within 5 working days if there is a problem with the mammogram.
- Only 1 or 2 mammograms out of every 1,000 lead to a diagnosis of cancer. Approximately 10% of women will require additional mammography. Don't be alarmed if this happens to you. Only 8%-10% of those women will need a biopsy, and 80% of those biopsies will not be 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 and/or request a reminder.
Clinical Breast Examination