Breast cancer health centre

Oncotype DX test for breast cancer

The Oncotype DX test is a way to check whether a person diagnosed with early breast cancer would benefit from chemotherapy.

Before the test became available, doctors had not been able to tell which people are at higher risk of breast cancer recurrence. Rather than take any chances, all patients would have a standard course of chemotherapy even though it may not be clear whether they'd benefit from it or not.

Chemotherapy often has toxic side effects for patients.

Who does the test help?

The Oncotype DX test is used in people with:

• Oestrogen receptor positive (ER+) breast cancer
• Lymph node negative (LN−) breast cancer
• Human epidermal growth factor receptor 2 negative (HER2−) early breast cancer.

Breast cancer and Oncotype DX

Oncotype DX is a diagnostic test that assesses the tumour tissue and estimates the likelihood that invasive breast cancer will return or recur after treatment. By analysing the pattern of certain genes in breast tumours, the Oncotype DX test can more precisely estimate a woman's risk of cancer recurrence when compared with the standard assessments doctors normally use to evaluate the risk of cancer returning.

The Oncotype DX screening test is performed on each tumour sample to get the Recurrence Score. The Oncotype DX test scores the breast tumour on 21 different genes involved in breast cancer. It then gives a Recurrence Score, or a number between 0 and 100, which shows the likelihood of breast cancer returning within 10 years of the original diagnosis.

The Recurrence Score is then categorised into one of three groups: low, intermediate or high risk. For example if a tumour has a Recurrence Score over 31, this is a high-risk score and means there is a greater chance that the breast cancer will return. If a tumour gets a Recurrence Score of 18 or less, a low-risk score, this indicates a lower chance that breast cancer will return.

Using the Recurrence Score as a measure of risk, researchers now see a correlation between the score and the type of cancer treatment required. For example with a low Recurrence Score, hormone therapy alone may successfully treat a woman's cancer. A high Recurrence Score indicates a greater chance of the breast cancer returning, so in this case the patient may benefit from adjuvant systemic therapy such as chemotherapy.