A mammogram is a special X-ray of the breast. It used to detect abnormal growths or changes in breast tissue. Mammograms are key to the early detection of breast cancer. A mammogram can detect cancers in the early stages, when they are too small to be felt during a breast examination. Breast cancer diagnosed at an early stage improves the chances of successful treatment.

 
During a mammogram, each breast is compressed between two plates and a low-dose X-ray image is made. This exam takes about 20 minutes to complete. A radiologist, who specializes in interpreting imaging studies, will read the X-ray films, looking for any signs of abnormal tissue. While a mammogram can identify areas of abnormal tissue, it cannot determine if cancer is present. A biopsy is necessary to confirm whether the abnormal area is cancerous. It is important to note that not all breast cancers can be detected by mammogram, especially in younger women who have dense breast tissue. A mammogram is, however, the most effective screening method available today.

There are two types of mammograms. A screening mammogram is used to look for breast disease in women who have no symptoms. A diagnostic mammogram evaluates the breasts of a woman who has symptoms of breast disease, such as a lump, or whose screening mammogram shows an abnormality.

The American Cancer Society recommends having a baseline mammogram between ages 35 and 40, and then every year after age 40.