Skip to main content

Breast Cancer

What Does the Doctor Look for on a Mammogram?

A radiologist will look at your mammogram. Radiologists are doctors who diagnose diseases and injuries using imaging tests such as x-rays. 

When possible, the doctor reading your mammogram will compare it to your old mammograms. This can help show if any findings are new, or if they were already there on previous mammograms. Findings that haven’t changed from older mammograms aren’t likely to be cancer, which might mean you won't need further tests. 

The doctor reading your mammogram will be looking for different types of breast changes, such as small white spots called calcifications, abnormal areas called masses, and other suspicious findings that could be signs of cancer.


Calcifications are tiny calcium 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 larger calcium deposits that are most likely due to changes caused by aging of the breast arteries, old injuries, or inflammation. These deposits are typically related to non-cancerous conditions and don’t need further testing with a biopsy. Macrocalcifications become more common as women get older (especially after age 50).


Microcalcifications are tiny specks of calcium in the breast. When seen on a mammogram, they are more of a concern than macrocalcifications, but they don’t always mean that cancer is present. The shape and layout of microcalcifications (and whether they are near a mass) help the radiologist judge how likely it is that the change is due to cancer.

In most cases, microcalcifications don’t need to be checked with a biopsy. But if they have a suspicious look and pattern, a biopsy will be recommended to check for cancer.


A mass is an area of abnormal breast tissue with a shape and edges that make it look different than the rest of the breast tissue on a mammogram. A mass might be seen with or without calcifications. Masses can be many things, including cysts (non-cancerous, fluid-filled sacs) and non-cancerous solid tumors (such as fibroadenomas), but they may also be a sign of cancer.

Cysts are fluid-filled sacs. Simple cysts (fluid-filled sacs with thin walls) are not cancer and typically don’t need to be checked with a biopsy. If a mass is not a simple cyst, it’s of more concern, so a biopsy might be needed to be sure it isn’t cancer.

Solid masses can be more concerning, but most solid breast masses are not cancer.

A cyst and a solid mass can feel the same. They can also sometimes look the same on a mammogram. The doctor must be sure it’s a cyst to know it’s not cancer, so a breast ultrasound is often done (because it is better than a mammogram at showing if the inside of a mass is solid or filled with fluid).

If it isn’t clear if the mass is a cyst or a solid mass, a thin, hollow needle may be inserted into the mass during an ultrasound to try to remove (aspirate) the fluid from the area. If the mass goes away on the ultrasound as the fluid is removed, then it is most likely a cyst and no further work up is needed.

If a mass is not a simple cyst (that is, if it’s at least partly solid, or if it has other concerning features), more imaging tests might be needed to decide if it could be cancer. Some masses can be watched over time with regular mammograms or ultrasound to see if they change, but others may need to be checked with a biopsy. The size, shape, and margins (edges) of the mass can help the radiologist decide how likely it is to be cancer.


Asymmetries are white areas seen on a mammogram that look different from the normal breast tissue pattern. There are different types of asymmetries, including focal asymmetry, developing asymmetry, and global asymmetry. 

Most of the time, these findings do not mean you have breast cancer. But more imaging tests will likely be needed to make sure there is no cancer in this area.

Architectural distortion

Radiologists use this term to describe when an area of the breast tissue appears distorted or pulled toward a certain point. Sometimes this may just be due to how the breast was positioned during the mammogram. It might also be caused by a prior injury or procedure done on the breast. But architectural distortion can also sometimes be a sign of a breast cancer, so further imaging with diagnostic mammograms is typically needed to get a better look at this area. 

Breast density

Your mammogram report will also contain an assessment of your breast density. Breast density is a measure of how much fibrous and glandular tissue is in your breast, compared to fatty tissue. It isn’t related to breast size or firmness.

Your breast tissue may be called ‘dense’ if you have more fibrous and glandular tissue compared to fatty tissue in the breast.

About half of all women have dense breasts. Having dense breasts is not abnormal. However, women who have dense breasts have a slightly higher risk of breast cancer.

Dense breast tissue can also make it harder to see cancers on a mammogram. This is because fibrous and glandular tissue appear white on a mammogram, which can hide many types of suspicious findings that also appear white. Still, experts don’t agree what other tests, if any, should be done along with mammograms in women with dense breasts who aren’t otherwise at higher risk for breast cancer (based on gene mutations, breast cancer in the family, or other factors).

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Esserman LJ, Joe BN. Diagnostic evaluation of suspected breast cancer. UpToDate. 2021. Accessed at on September 29, 2021.

Helvie MA, Patterson SK. Chapter 11: Imaging Analysis: Mammography. In: Harris JR, Lippman ME, Morrow M, Osborne CK, eds. Diseases of the Breast. 5th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2014.

Venkataraman S, Slanetz PJ, Lee CI. Breast imaging for cancer screening: Mammography and ultrasonography. UpToDate. 2021. Accessed at on September 29, 2021.

Last Revised: January 14, 2022

American Cancer Society Emails

Sign up to stay up-to-date with news, valuable information, and ways to get involved with the American Cancer Society.