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, larger abnormal areas called masses, and other suspicious areas that could be signs of cancer.

Calcifications

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

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 to be checked for cancer with a biopsy. Macrocalcifications become more common as women get older (especially after age 50).

Microcalcifications

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 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.

Masses

A mass is an area of dense breast tissue with a shape and edges that make it look different than the rest of the breast tissue. With or without calcifications, it’s another important change seen on a mammogram. 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 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 breast masses are not cancer.

A cyst and a solid mass can feel the same. They can also look the same on a mammogram. The doctor must be sure it’s a cyst to know it’s not cancer. To be sure, a breast ultrasound is often done because it is a better tool to see fluid-filled sacs. Another option is to use a thin, hollow needle to remove (aspirate) fluid from the area.

If a mass is not a simple cyst (that is, if it’s at least partly solid, or 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.

Breast density

Your mammogram report will also contain an assessment of your breast density. Breast density is based on how fibrous and glandular tissues are distributed in your breast, compared to how much of your breast is made up of fatty tissue.

Dense breasts are not abnormal, but they are linked to a higher risk of breast cancer. Dense breast tissue can also make it harder to find cancers on a mammogram. 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.

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.

Last Medical Review: October 3, 2019 Last Revised: October 3, 2019

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