Oncotype Dx is a test that helps predict the chance of metastasis (when cancer spreads to other organs) for some breast cancers. It tests a sample of the tumor (removed during a biopsy or surgery) for a group of 21 genes. Along with other prognostic and diagnostic factors, the results of the Oncotype Dx test can be used to tailor treatment plans.
If the test shows a person has a fairly high risk of metastasis (the Oncotype DX score is high), a more aggressive treatment plan that includes both hormone therapy and chemotherapy may be advised [33-36]. If the test shows a low risk of metastasis (the Oncotype DX score is low), the use of hormone therapy alone may be considered. In this way, Oncotype Dx may help some people avoid chemotherapy and its side effects.
Oncotype Dx helps predict the chance of metastasis for breast cancers that are all of the following [31-33]:
Oncotype DX may also be used in select postmenopausal women with invasive breast cancers that are all of the following [33-36]:
- Stage II or IIIa and
- Estrogen receptor-positive (and will be treated with hormone therapy) and
- HER2/neu-negative and
- Lymph node-positive
Although Oncotype Dx can provide some prognostic information in select premenopausal women with lymph node-positive breast cancers, it is not used to guide treatment for these women. Researchers have not yet studied whether it can help predict chemotherapy benefit for lymph node-positive premenopausal breast cancers.
Active areas of study
Researchers are studying whether Oncotype DX can predict how well breast cancers will respond to different chemotherapy drugs.
The Oncotype DX test for invasive breast cancer has been modified to help predict the chance that ductal carcinoma in situ (DCIS) will return as DCIS or invasive breast cancer . This could help identify which cases of DCIS would benefit most from radiation therapy after lumpectomy (and which women might be treated with lumpectomy alone) . This test needs further study and is not yet part of standard practice.