- What is a mammogram?
- What’s the difference between a screening mammogram and a diagnostic mammogram?
- How is a mammogram done?
- What to expect when you have a mammogram
- Where can I get help with mammogram costs?
- How is mammography regulated?
- What does the doctor look for on a mammogram?
- What if a breast biopsy is needed?
- Understanding your mammogram report – BI-RADS categories
- What are the limitations of mammograms?
- Mammograms in special circumstances
- Newer techniques for improving mammograms
- When are other breast imaging tests used?
- Experimental and other breast imaging methods
- To learn more
What does the doctor look for on a mammogram?
A mammogram may show something suspicious, but by itself it can’t prove that an abnormal area is cancer. If a mammogram raises a suspicion of cancer, a tissue sample from the suspicious area must be removed and looked at under the microscope to find out if it is cancer. For detailed information on the types of biopsies and what you need to know, please see our document For Women Facing a Breast Biopsy.
The doctor reading your mammogram will look for different types of changes.
Calcifications are tiny mineral deposits within the breast tissue. They look like small white spots on a mammogram. They may or may not be caused by cancer. There are 2 types of calcifications.
Macrocalcifications are coarse (larger) calcium deposits that are most likely due to changes in the breasts caused by aging of the breast arteries, old injuries, or inflammation. These deposits are related to non-cancerous conditions and do not require a biopsy. Macrocalcifications are found in about half the women over 50, and in 1 of 10 women under 50.
Microcalcifications are tiny specks of calcium in the breast. Microcalcifications seen on a mammogram are of more concern than macrocalcifications, but they 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 cases, the presence of microcalcifications does not mean a biopsy is needed. But if the microcalcifications have a suspicious look and pattern, a biopsy will be recommended. (During a biopsy, the doctor removes a small piece of the suspicious area to be looked at under a microscope. A biopsy is the only way to tell if cancer is really present.)
A mass, 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), but may sometimes may be a sign of cancer.
Cysts can be simple fluid-filled sacs (known as simple cysts) or can be partially solid (known as complex cysts). Simple cysts are benign (not cancer) and don’t need to be biopsied. If a mass is not fluid-filled, it is of more concern and might need to be biopsied to be sure it isn’t cancer.
- A cyst and a tumor can feel the same 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’s at least partly solid), more imaging tests may be needed. Some masses can be watched with regular mammograms or ultrasound, while others may need a biopsy. The size, shape, and margins (edges) of the mass may help the radiologist determine if cancer is likely to be present.
Having your prior 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’s likely not cancer and a biopsy is not needed.
Your mammogram report will also contain an assessment of breast density. Breast density is based on how fibrous and glandular tissue tissues are distributed in your breast, vs. how much of your breast is made up fatty tissue.
Dense breasts are not abnormal, but they are linked to a higher risk of breast cancer. We know that dense breast tissue can make it harder to find cancers on a mammogram. Still experts do not agree what other tests, if any, should be done in addition to mammograms in women with dense breasts who aren’t in a high-risk group (based on gene mutations, breast cancer in the family, or other factors).
Last Medical Review: 12/10/2013
Last Revised: 11/05/2014