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. Doctors call treatments given after surgery adjuvant treatments.
The Oncotype DX test results assign a Recurrence Score -- a number between 0 and 100 -- to the early-stage breast cancer. Doctors use the following ranges to interpret the 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.
Because the Oncotype DX test has been validated by much research, right now it is the most widely used genomic test. Researchers wanted to know about trends in the test’s use, as well as the test’s effect on adjuvant chemotherapy recommendations.
A study has found that while Oncotype DX test results strongly influence whether doctors recommend chemotherapy after surgery or not, black women are less likely to receive the test.
The research was published online on March 21, 2016 by the Journal of Clinical Oncology. Read the abstract of “21-Gene Recurrence Score Assay As a Predictor of Adjuvant Chemotherapy Administration for Early-Stage Breast Cancer: An Analysis of Use, Therapeutic Implications, and Disparity Profile.”
To do the study, the researchers looked at the National Cancer Data Base and found 143,032 women that had been diagnosed with early-stage, estrogen-receptor-positive, HER2-negative breast cancer from 2004 to 2012. The National Cancer Data Base is sponsored by the Commission on Cancer of the American College of Surgeons and the American Cancer Society and captures about 70% of all newly diagnosed cancers in the United States from approximately 1,500 hospitals accredited by the Commission on Cancer.
Of the 143,032 diagnosed women, Oncotype DX testing was ordered for 77,308 of them -- about 54%.
Women less likely to have Oncotype DX testing were:
- of another non-white race
- covered by governmental health insurance (instead of private insurance)
Women more likely to have Oncotype DX testing were:
- treated at an academic research facility
- covered by private insurance
- diagnosed with larger tumors that had a higher grade
Of the women for whom Oncotype DX testing was ordered, 6,337 (about 8%) didn’t meet the recommended guidelines for Oncotype testing. These women were diagnosed with breast cancer that was:
- estrogen-receptor-negative and HER2-positive
- larger than 5 cm
The Oncotype DX test can’t predict how cancers with the above characteristics will behave, so isn’t recommended for them.
Black women and women treated at community facilities were more likely to have Oncotype DX testing that was done outside the recommended guidelines.
The researchers found that Oncotype DX test results were an important predictor of whether a woman diagnosed with early-stage, estrogen-receptor-positive, HER2-negative disease would be treated with chemotherapy after surgery. The Oncotype DX test influenced doctors’ decisions about adjuvant chemotherapy more than the other factors the researchers looked at, including tumor grade and size.
Younger black women were more likely to be treated with chemotherapy after surgery, even if they had a low Recurrence Score.
"We meant this study as a kind of state of the union for the use of this test," said Jagar Jasem, M.D., M.P.H., University of Colorado Cancer Center resident and the study's lead author. "What we found were some pretty stark disparities along socioeconomic and racial lines.
"We show that doctors are absolutely using this test to decide who gets chemotherapy along with their treatment," he continued. "In fact, of all the variables we explored, this test was most strongly associated with the chance that a patient goes on to receive chemotherapy. But what we show is that the treatment of minority and low socioeconomic patients is more likely to be disconnected from these test results."
While it’s encouraging that doctors are using Oncotype DX test score results to make decisions about chemotherapy after surgery for early-stage, estrogen-receptor-positive, HER2-negative disease, it’s troubling that the test isn’t being evenly used among all ethnic and socioeconomic groups.
If you’ve been diagnosed with early-stage, hormone-receptor-positive 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. If your doctor hasn’t recommended an Oncotype DX or other genomic test for you, you may want to ask why. 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.
For more information, visit the Breastcancer.org Onctoype DX page.