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. 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 shows that women with an Oncotype DX test Recurrence Score between 0 and 10 can safely be treated only with hormonal therapy, allowing them to skip chemotherapy.
The study was published online on Sept. 28, 2015 by the New England Journal of Medicine. Read “Prospective Validation of a 21-Gene Expression Assay in 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.
In this study, called the TAILORx (Trial Assigning IndividuaLized Options for Treatment), included more than 10,000 women diagnosed with early-stage, hormone-receptor-positive, HER2-negative breast cancer that hadn’t spread to the lymph nodes. The researchers performed Oncotype DX texts on tissues samples from all the cancers and all the women were then assigned an Oncotype DX Recurrence Score:
- women with a Recurrence Score of 0 to 10 were assigned to receive hormonal therapy alone (meaning they didn’t get chemotherapy) -- 1,626 women were in this group (15.9% of the women in the study)
- women with a Recurrence Score of 11 to 25 were randomly assigned to received either:
- chemotherapy plus hormonal therapy
- hormonal therapy alone
6,897 women were in this group (67.3% of the women in the study)
- women with a Recurrence Score of 26 or higher were assigned to receive chemotherapy plus hormonal therapy -- 1,730 women were in this group (16.9% of the women in the study)
Earlier studies have shown that women with a Recurrence Score of 10 or lower had good outcomes when treated with hormonal therapy alone and that women with a Recurrence Score of 26 or higher benefitted from chemotherapy and these benefits outweighed the risk of side effects. It’s been unclear whether women with a Recurrence Score of 11 to 25 would benefit from chemotherapy, which is why the researchers randomly assigned the women in this group to hormonal therapy alone or hormonal therapy plus chemotherapy.
The women with a Recurrence Score of 0 to 10 were treated with different types of hormonal therapy:
- 59% of the women took an aromatase inhibitor
- 34% took tamoxifen
- 1% took tamoxifen first, then switched to an aromatase inhibitor
- 3% took medicine to stop their ovaries from making estrogen
After 5 years, less than 2% of the women had the cancer come back (recurrence). Overall survival -- how many women were alive with or without the cancer coming back -- also was 98%.
The researchers who did the study said the results provide the highest level of evidence that an Oncotype DX Recurrence Score of 0 to 10 means that those women can safely avoid chemotherapy.
"The compelling results seen in this global study provide unequivocal evidence supporting the clinical utility of Oncotype DX to risk-stratify patients with early-stage breast cancer, and indicate that the findings are generalizable to everyday clinical practice," said lead author Joseph A. Sparano, M.D., vice-chairman of medical oncology at Montefiore Einstein Center for Cancer Care, and professor of medicine and of obstetrics, gynecology, women's health at Albert Einstein College of Medicine. "This is the first prospectively conducted clinical trial evaluating this assay -- or any multigene expression assay for that matter -- in which patients with early stage breast cancer were uniformly treated based on their assay results. The findings provide the highest level of evidence supporting expert-derived clinical practice guidelines which have recommended Oncotype DX in patients with early stage ER-positive breast cancer.”
The researchers will continue to follow the women in the study to determine whether women with a Recurrence Score of 11 to 25 also can skip chemotherapy or whether they benefit from it.
“For those seeking confirmation that this assay can identify a cohort of patients who should be spared chemotherapy, this result is both reassuring and frustrating,” said Clifford Hudis, M.D., chief of the Breast Cancer Medicine Service at Memorial Sloan-Kettering Cancer Center, in an invited commentary that was published along with the research article. Dr. Hudis also is a member of the Breastcancer.org Professional Advisory Board.
He continued, “For patients in this new ‘lower risk’ group, it is clearly helpful, if broadly anticipated. However, for the many physicians already using the test, the gap between this cutoff point of 10 and the higher ‘standard’ cutoff point of 18 may be a concern. Some others will wonder whether chemotherapy is beneficial or indicated even in patients with scores up to 25. If chemotherapy is effective in this newly defined intermediate-risk group (score 11 to 25), then examination of the subgroup of patients with scores of 11 to 17 will be critical, since there will be two conflicting guides to their treatment that need to be reconciled: the cutoff point used in this trial and the previously available cutoff point that is associated with the commercial test.”
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. 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.