For Women Facing a Breast Biopsy

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Appendix C: Mammograms: Finding hidden breast cancer

One of the best things a woman can do to defend herself against breast cancer is get regular screening mammograms.

What is a mammogram?

A mammogram is a special x-ray that makes a picture of the inside of the breast. Mammograms use radiation, but the amount is very low. The potential harm from this small amount of radiation is very small and far outweighed by the potential benefit.

Mammograms can be done in a radiology facility, a hospital or clinic, or a doctor’s office. There are 2 kinds of mammograms:

    A screening mammogram is an x-ray of the breast of a woman who has no breast symptoms or problems. Because most breast cancers don’t cause symptoms, a screening mammogram may be the best way for most women to find cancers early, when they are small, have not spread, and are most treatable.

    A diagnostic mammogram is used to find breast disease in women who have symptoms or areas of change on their screening mammogram. Diagnostic mammograms help the health care provider learn more about breast lumps or the cause of other breast symptoms.

Women who have a family history of breast cancer, a genetic tendency, or certain other factors may need to start testing for breast cancer when they are young. They may also need to be screened with an MRI along with a mammogram. Talk with a health care provider about your history and the screening tests and schedule that are best for you.

Mammogram results

When health care providers look at mammograms, they compare the x-rays from previous mammograms and look for differences between the breast images. Sometimes the x-ray will show tiny bits of calcium in the breast called microcalcifications. Most microcalcifications are harmless, but in some cases, they can be a sign of cancer or a pre-cancerous change. The provider looks at the shape and arrangement of the microcalcifications to decide if a biopsy is needed.

Sometimes, the provider sees an area of the breast that looks a little different but not enough to report the mammogram as abnormal. When this happens, the doctor may ask that the mammogram be repeated in about 4 to 6 months.

The mammogram may also show the presence of a mass, or suspicious-looking area of tissue. Masses or lumps are not a sure sign of cancer. The health care provider will look at the size, shape, and margins (edges) of the mass to figure out the likelihood of cancer. More testing may be needed to find out if it’s cancer.

Mammograms are the best way for most women to check for breast cancer in its early stages, but a mammogram alone cannot prove that breast change is cancer. If cancer is suspected, more testing will be needed.


  • Some women will need to have more tests or another mammogram after the first one is taken. Don’t be alarmed if this happens to you. Being called back for more testing does not mean that you have cancer. Sometimes this happens if there is a technical problem with the x-ray film, or if the film was hard to read.
  • Very few women who need repeat mammograms will need a biopsy, and most of those biopsies will not be cancer.
  • Breast cancer can be cured, especially if it’s caught early.

Last Medical Review: 07/21/2014
Last Revised: 10/20/2015