Oncotype DX Test for Breast Cancer

Medically Reviewed by Sabrina Felson, MD on February 13, 2024
Written by WebMD Editorial Contributors
3 min read

If you’re diagnosed with breast cancer, your doctor may recommend the Oncotype DX test. Depending on the type cancer you have, the test can tell doctors if the cancer is likely to come back at some point. 

The Oncotype DX analyzes a sample of a cancer tumor to see the activity of certain genes that can affect the cancer's outcome and how likely it is to grow and spread. The test uses tissue taken during the initial biopsy or surgery. It measures the breast cancer genes. (You might hear it called a "21-gene signature.") Your doctor might suggest the test if you have:

 

  • Stage I or II invasive breast cancer
  • Estrogen-receptor positive (called ER+) cancer, meaning the disease's cells grow in response to the hormone estrogen
  • Cancer that isn’t in the lymph nodes

 

You may also have the test if you’ve recently been diagnosed with ductal carcinoma in situ (DCIS). It can help in deciding whether you have radiation treatments.

The test looks at 21 different genes within the cells of a tumor sample. Certain patterns suggest a more aggressive cancer that is more likely to come back after treatment. The test results show a score between 0 and 100.

If you have early-stage invasive breast cancer and are over 50 years old, the scoring is as follows:

  • A score between 0 and 25 means you have a low risk of the cancer returning if you get hormone treatment.  With this score you probably will not benefit from receiving chemotherapy.
  • A score between 26 and 100 means you have a higher risk that the disease might come back.  Both hormone treatment and chemotherapy are likely to be recommended.

If you have early stage invasive breast cancer and are age 50 or younger, the scoring is as follows:

  • A score of 15 or smaller means you have a low risk of the cancer returning if you get hormone treatment. You probably will not benefit from receiving chemotherapy.
  • A score between 16 and 20 means you have a low to medium risk of the cancer returning if you get hormone treatment.  There may be a small benefit of receiving chemotherapy, but the benefits may not outweigh the risks of side effects.
  • A score between 21 and 25 means you have a medium risk of the cancer returning if you get hormone treatment.  The benefits of chemotherapy may outweigh the risk of side effects.
  • A score between 26 and 100 means you have a higher risk that the disease might come back.  Both hormone treatment and chemotherapy are likely to be recommended.

 

The results of your tests alone aren’t enough to determine your treatment. Your doctor will also consider the tumor size and grade, the number of hormone receptors in your cancer, and your age before recommending a treatment plan.

 

Other genome tests show promise in helping treat early-stage breast cancer, but more research is needed.

MammaPrint looks at 70 different genes within the cells of a breast tumor and helps predict whether cancer is likely to spread beyond the breast. This test can be used for tumors that are ER+ or ER-.

The Mammostrat test measures five genes to determine the risk for early-stage hormone receptor-positive disease coming back.

The Prosigna assay looks at early-stage hormone receptor-positive disease in postmenopausal women (with up to three positive lymph nodes). It analyzes 58 genes and calculates the risk of cancer coming back somewhere else in the body within 10 years of diagnosis after hormone therapy.