The Who, What, Where, When and Sometimes, Why.


MammaPrint® is a tumor profiling test that helps predict how likely some estrogen receptor-positive (ER-positive), HER2-negative early breast cancers are to metastasize (spread to other organs).

Tumor profiling

Every cell in your body has genes that contain the blueprints (genetic code) for your body. Similarly, every cell in a breast tumor has genes. These genes contain the blueprints for the cancer.

Tumor profiling (using gene expression profiling tools) gives information about the genes in cancer cells. You may also hear the terms genomic testing and molecular profiling.

MammaPrint is a tumor profiling test.

MammaPrint testing

MammaPrint tests a sample of the tumor (removed during a biopsy or surgery) for a group of 70 genes. These genes are in the tumor cells, not in the normal (non-cancer) cells in a person’s body.

The results of the MammaPrint test help predict the chance of metastasis for some ER-positive, HER2-negative breast cancers.

MammaPrint results

For some women ages 51 and older, if the MammaPrint results show a fairly high risk of metastasis, a more aggressive treatment plan that includes both hormone therapy and chemotherapy may be advised [33]. However, for women ages 50 and younger, it’s unclear if a benefit of adding chemotherapy is due to the chemotherapy or the ovarian suppression caused by the chemotherapy [14,33].

If the MammaPrint results show a low risk of metastasis, the use of hormone therapy alone may be considered [14].

In this way, MammaPrint may help some people avoid chemotherapy and its side effects.

When can MammaPrint be used?

MammaPrint helps predict the chance of future metastasis for some breast cancers at high clinical risk of recurrence, based on estrogen receptor status, HER2 status, tumor grade, lymph node status and tumor size [33,39]. MammaPrint can be used for high clinical risk breast cancers that are all of the following [33,39]:

  • Tumor size no larger than 5 cm (or if larger, can be removed with surgery)
  • ER-positive (and will be treated with hormone therapy) 
  • HER2-negative
  • Lymph node-negative or lymph node-positive with 1-3 positive nodes

Updated 12/20/22