The Oncotype DX test is a genomic test that analyzes the activity of a group of 21 genes from a breast cancer tissue sample that can affect how a cancer is likely to behave and respond to treatment.
Doctors use the Oncotype DX test to help figure out a woman’s risk of early-stage, estrogen-receptor-positive, HER2-negative breast cancer coming back (recurrence), as well as how likely she is to benefit from chemotherapy after breast cancer surgery.
Most early-stage, estrogen-receptor-positive, HER2-negative breast cancers that haven’t spread to the lymph nodes are considered to be at low risk for recurrence. After surgery, hormonal therapies such as an aromatase inhibitor or tamoxifen are prescribed to reduce the risk that the cancer will come back in the future. Whether or not chemotherapy also is necessary has been an area of uncertainty for patients and their doctors, especially for women with cancer that had spread to just one, two, or three lymph nodes. The Oncotype DX test was designed to offer more information to help women and their doctors make decisions about chemotherapy.
The Oncotype DX test results assign a Recurrence Score -- a number between 0 and 100 -- to the early-stage breast cancer. You and your doctor can use the following ranges to interpret your results for early-stage invasive cancer:
- Recurrence Score lower than 18: The cancer has a low risk of recurrence. The benefit of chemotherapy is likely to be small and will not outweigh the risks of side effects.
- Recurrence Score of 18 up to and including 30: The cancer has an intermediate risk of recurrence. It’s unclear whether the benefits of chemotherapy outweigh the risks of side effects.
- Recurrence Score greater than or equal to 31: The cancer has a high risk of recurrence, and the benefits of chemotherapy are likely to be greater than the risks of side effects.
A prospective study has found that women with a Recurrence Score of 11 or lower who skipped chemotherapy based on the Recurrence Score had excellent 3-year and 5-year survival rates.
Three-year survival rates from the research were published online on Feb. 29, 2016 by the Journal of Clinical Oncology. Read the abstract of “West German Study Group Phase III PlanB Trial: First Prospective Outcome Data for the 21-Gene Recurrence Score Assay and Concordance of Prognostic Markers by Central and Local Pathology Assessment.”
More recent 5-year survival rates from the same study were presented on March 11, 2016 at the 2016 European Breast Cancer Conference. Read the abstract of “Prospective WSG Phase III PlanB trial: Clinical outcome at 5 year follow up and impact of 21 Gene Recurrence Score result, central/local-pathological review of grade, ER, PR and Ki67 in HR+/HER2- high risk node-negative and -positive breast cancer.”
A prospective study follows a group of similar people who are different in terms of the factors being studied to see how the factors affect the rates of a certain outcome.
The study, called the PlanB study, included 3,198 women diagnosed with early-stage, hormone-receptor-positive, HER2-negative breast cancer that was either node-positive (cancer was found in the lymph nodes) or node-negative with other characteristics that classified the cancer as having a high risk of recurrence.
The women’s ages ranged from 18 to 76. Oncotype DX testing was done on tissue samples from 2,568 cancers:
- 15.3% had a Recurrence Score of 11 or lower (defined by the researchers as a low risk of recurrence)
- 60.4% had a Recurrence Score of 12 to 25 (defined by the researchers as an intermediate risk of recurrence
- 21.6% had a Recurrence Score of higher than 25 (defined by the researchers as a high risk of recurrence)
Women who had an Oncotype DX Recurrence Score of 11 or lower weren’t treated with chemotherapy based on the Recurrence Score. These women were treated only with hormonal therapy after surgery.
The researchers assumed that after 5 years, more than 90% of the women who skipped chemotherapy should be alive with no recurrence (disease-free survival).
After about 3 years of follow-up, disease-free survival rates were:
- 98% for women with a Recurrence Score of 11 or lower who were treated only with hormonal therapy
- 97.8% for women with a Recurrence Score of 12 to 25 who were treated with hormonal therapy and chemotherapy
- 91.9% for women with a Recurrence Score of 26 and higher who were treated with hormonal therapy and chemotherapy
After about 5 years of follow-up, disease-free survival rates were:
- 94% for women with a Recurrence Score of 11 or lower
- 94% for women with a Recurrence Score of 12 to 25
- 84% for women with a Recurrence Score of 26 and higher
These results confirm similar findings from the TAILORx study, which involved women with node-negative, early-stage, hormone-receptor-positive, HER2-negative disease.
"In this prospective trial for patients who had a clinically determined intermediate or high risk of recurrence and who had zero to three lymph nodes involved, we have been able identify about 15% who were assessed by the 21-gene RS as being at low genomic risk," said Dr. Oleg Gluz, the lead author of the study. "We were thus able to treat them by anti-hormonal therapy alone and to spare them chemotherapy. The 94% disease-free survival rate that we observe after five years without adjuvant chemotherapy is an excellent result."
When the researchers compared other characteristics of the cancer, such as size and grade, they found that the Oncotype DX test was a better predictor of disease recurrence, whether it was used on its own or in combination with the cancer characteristics.
"This very important trial adds to the evidence from the low-risk arm of the TAILORx study, and to a wealth of other retrospective studies, supporting the use of genomic testing to help accurately select early breast cancer patients who can safely be spared chemotherapy," said Dr. Fatima Cardoso, director of the Breast Unit at the Champalimaud Clinical Centre in Portugal, who is also chair of the European Breast Cancer Conference.
If you’ve been diagnosed with early-stage, hormone-receptor-positive, HER2-negative breast cancer and are weighing the pros and cons of adding chemotherapy to your treatment plan, the Oncotype DX test may help you and your doctor make that decision. Besides any genomic test results, you and your doctor will consider other factors when developing your treatment plan, such as:
- your age
- the size of the cancer
- hormone-receptor protein levels
- the grade of the cancer
- any other health conditions you have
- your personal preferences
Together, you can make the best treatment decisions for YOU.
You can learn more on the Breastcancer.org Oncotype DX Test page.