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Breast Cancer Gene Expression Tests
Gene expression tests are done on breast cancer cells after surgery or biopsy to look at the patterns of different genes. This process might also be called gene expression profiling.
These tests are a form of personalized medicine. Personalized medicine involves learning more about your specific cancer to tailor your treatment.
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How are gene expression tests helpful?
Gene expression tests can help people with early-stage breast cancer in multiple ways, and more are being studied.
Predict whether the cancer might come back (recur)
The patterns found can help predict if certain early-stage breast cancers are likely to recur after initial treatment.
Help choose treatment
Hormone therapy is a standard treatment for hormone receptor-positive breast cancers, but it’s not always clear when to use chemotherapy. Some gene expression tests can help predict which people will most likely benefit from chemotherapy after breast surgery (adjuvant chemotherapy). Still, these tests cannot tell for certain if a cancer will come back with or without chemotherapy.
These tests continue to be studied in large clinical trials to better understand how and when to best use them. Ask your doctor if these tests might be useful for you.
Testing options
The Oncotype DX, MammaPrint, Prosigna, EndoPredict, and Breast Cancer Index (BCI) are examples of gene expression tests that can be used to decide if chemotherapy or longer treatment with hormone therapy is needed to reduce the risk of breast cancer recurrence. These tests are used for early-stage cancers, and testing isn’t needed in all cases.
The type of test that's used will depend on your situation. For example, if breast cancer is advanced, it might be clear that chemotherapy is needed, even without gene expression testing.
The Oncotype DX test is used for early-stage hormone receptor-positive tumors that have not spread to more than 3 lymph nodes and are HER2-negative. It can also be used for DCIS (ductal carcinoma in situ or stage 0 breast cancer).
This test looks at a set of 21 genes in cancer cells to get a recurrence score, which is a number between 0 and 100. The score reflects the risk of breast cancer recurring in the next 9 years if you are treated with hormone therapy alone and how likely you are to benefit from getting chemotherapy after surgery.
For people over 50 with hormone receptor-positive, HER2-negative breast cancer that has either not spread to the lymph nodes or spread to no more than 3 lymph nodes:
- A low score (0-25) means a low risk of recurrence. Most people with low recurrence scores do not benefit from chemotherapy and have good outcomes when treated with hormone therapy.
- A high score (26-100) means a higher risk of recurrence. People with high recurrence scores are more likely to benefit from the addition of chemotherapy to hormone therapy to help lower the chance of recurrence.
For people 50 and younger with hormone receptor-positive, HER2-negative breast cancer that has not spread to the lymph nodes:
- A low score (0-15) means a low risk of recurrence. Most people with low recurrence scores do not benefit from chemotherapy and have good outcomes when treated with hormone therapy.
- An intermediate score (16-25) means that some people in this group might have a small benefit from adding chemotherapy to hormone therapy to lower the risk of recurrence. Talk to your doctor about options.
- A high score (26-100) means a higher risk of recurrence. People with high recurrence scores are more likely to benefit from the addition of chemotherapy to hormone therapy to help lower the chance of recurrence.
For people 50 and younger with hormone receptor-positive, HER2-negative breast cancer that has spread to no more than 3 lymph nodes:
- A low score (0-25) means a lower risk of recurrence. People in this group might benefit from adding chemotherapy to hormone therapy. Another option might be ovarian suppression along with tamoxifen or an aromatase inhibitor.
- A high score (26-100) means a higher risk of recurrence. People in this group are more likely to benefit from the addition of chemotherapy to hormone therapy to help lower the chance of the cancer coming back.
Some doctors disagree about whether these test results are needed for younger people with breast cancer that has spread to the lymph nodes, since chemotherapy might be a good option regardless of the results. Talk to your cancer team about how the results might affect your treatment plan.
The MammaPrint test can be used to help determine how likely early-stage breast cancers are to recur in a distant part of the body after treatment. It can be used for breast cancer in people older than 50 that is hormone-positive, HER2-negative, and has spread to no more than 3 lymph nodes.
The test looks at 70 different genes to determine whether the cancer is at low risk or high risk of recurring in the next 10 years. This test is being used to guide decisions about treatment with hormone therapy and chemotherapy.
The Prosigna test can be used to predict the risk of recurrence in the next 10 years in women who have gone through menopause (postmenopausal) and whose early-stage invasive breast cancers are hormone receptor-positive and HER2 negative.
The test looks at 50 genes. In hormone receptor-positive and HER2 negative tumors that have not spread to the lymph nodes, the results can be classified as low, intermediate, or high risk. If the cancer has spread to no more than 3 lymph nodes, the result of this test can be either low or high risk of recurrence.
The EndoPredict test can be used to guide decisions about hormone therapy and chemotherapy use in people over the age of 50 with early-stage breast cancers that are hormone-positive, HER2 negative, and have spread to no more than 3 lymph nodes.
This test looks for 12 genes, and the results can be either a high or low risk of recurrence over the next 10 years.
The Breast Cancer Index test is used to predict the risk of recurrence in the 5 to 10 years after diagnosis in people whose invasive breast cancers are hormone receptor-positive and have not spread to more than 3 lymph nodes.
It can also help predict who might benefit from hormone therapy for longer than 5 years.
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- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
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Last Revised: July 23, 2026
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