The Oncotype DX test is a genomic test that analyzes the activity of 21 genes that can affect how a cancer is likely to behave and respond to treatment. The Oncotype DX test is used:
- to help doctors figure out a woman’s risk of early-stage, estrogen-receptor-positive breast cancer coming back (recurrence), as well as how likely she is to benefit from chemotherapy after breast cancer surgery
Oncotype DX test results assign a Recurrence Score -- a number between 0 and 100 -- to the early-stage breast 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.
There is also an Oncotype DX DCIS test that is used to help predict the risk of DCIS recurrence.
A study has found that the Oncotype DX Recurrence Score can help predict the risk of late distant recurrence in women diagnosed with stage I or stage II, estrogen-receptor-positive breast cancer that highly expresses gene ESR1 and has been treated with 5 years of tamoxifen. Late distant recurrence is breast cancer that comes back in a part of the body away from the breast more than 5 years after initial diagnosis.
The ESR1,or Estrogen Receptor 1, gene encodes an estrogen receptor, so cancers that highly express the ESR1 gene have more estrogen receptors and are more strongly estrogen-receptor-positive.
The research was published online on May 23, 2016 by the Journal of Clinical Oncology. Read the abstract of “Prognostic Impact of the Combination of Recurrence Score and Quantitative Estrogen Receptor Expression (ESR1) on Predicting Late Distant Recurrence Risk in Estrogen Receptor-Positive Breast Cancer After 5 Years of Tamoxifen: Results from NRG Oncology/National Surgical Adjuvant Breast and Bowel Project B-28 and B-14.”
Studies have shown that estrogen-receptor-positive breast cancer has a more drawn out risk of recurrence compared to estrogen-receptor-negative disease. About 50% of estrogen-receptor-positive disease recurrences happen 5 or more years after the initial diagnosis. Most estrogen-receptor-negative disease recurrences happen within the first 5 years after initial diagnosis.
So researchers wanted to know if the Oncotype DX recurrence score could help doctors figure out which women had a higher risk of late distant recurrence and would likely benefit from 5 more years (for a total of 10 years) of hormonal therapy and which women had a lower risk of late distant recurrence and who might be able to stop hormonal therapy after 5 years.
The analysis reviewed here looked at Recurrence Score information from two studies:
- NSABP B-28: 1,065 women diagnosed with estrogen-receptor-positive, stage I or stage II breast cancer treated with chemotherapy followed by 5 years of tamoxifen; follow-up was about 11 years
- NSABP B-14: 668 women diagnosed with estrogen-receptor-positive, stage I or stage II breast cancer treated with 5 years of tamoxifen; follow-up was about 14 years
Of the 1,065 women in the B-28 study:
- 36% had a low (17 or lower) Recurrence Score
- 34% had an intermediate (18-30) Recurrence Score
- 30% had a high (31 or higher) Recurrence Score
Of the 668 women in the B-14 study:
- 51% had a low Recurrence Score
- 22% had an intermediate Recurrence Score
- 27% had a high Recurrence Score
There were 359 distant recurrences in the B-28 study, and 168 of the recurrences (47%) happened more than 5 years after initial diagnosis (late distant recurrence).
There were 109 distant recurrences in the B-14 study, and 50 of them (46%) happened more than 5 years after initial diagnosis (late distant recurrence).
In the B-28 study, the Recurrence Score was linked to the risk of distant recurrence up to 5 years after diagnosis for cancers with high and low expression of ESR1. So the lower the Recurrence Score, the lower the risk of distant recurrence. More than 5 years after diagnosis, the Recurrence Score was linked to the risk of distant recurrence only for cancers that highly expressed ESR1. Five to 10 years after initial diagnosis, the risk of distant recurrence for cancers that highly expressed ESR1 was:
- 10.5% for women with low Recurrence Scores
- 22.5% for women with intermediate Recurrence Scores
- 22.6% for women with high Recurrence Scores
Results from women in the B-14 study echoed results from the B-28 study: Recurrences Scores were linked to the risk of distant recurrence up to 5 years after diagnosis for cancers with high and low expression of ESR1. More than 5 years after initial diagnosis, the recurrence score was linked to the risk of distant recurrence only for cancers that highly expressed ESR1. Five to 10 years after initial diagnosis, the risk of distant recurrence for cancers that highly expressed ESR1 was:
- 4.7% for women with low Recurrence Scores
- 4.1% for women with intermediate Recurrence Scores
- 12.6% for women with high Recurrence Scores
Five to 15 years after initial diagnosis, the risk of distant recurrence for cancers that highly expressed ESR1 was:
- 6.8% for women with low Recurrence Scores
- 11.2% for women with intermediate Recurrences Scores
- 16.4% for women with high Recurrence Scores
Right now, guidelines from the American Society of Clinical Oncology recommend that all women diagnosed with hormone-receptor-positive disease be offered the option of taking hormonal therapy for 10 years.
This study suggests that there may be some women diagnosed with stage I or stage II, hormone-receptor-positive breast cancer with low ESR1 expression that may be able to take only 5 years of hormonal therapy. While these results are promising, more research is necessary before doctors know for sure which women can safely have only 5 years of hormonal therapy.
If you’ve been diagnosed with hormone-receptor-positive breast cancer and will be taking hormonal therapy after surgery and other treatments, it’s very important that you take the medicine for as long as it’s prescribed and at the dose at which it is prescribed. As this study shows, hormone-receptor-positive breast cancer can come back -- even after 5 or 10 years -- and hormonal therapy after surgery reduces that risk. You must remember that.
Side effects caused by hormonal therapy can be very troublesome for many women. It’s important to talk to your doctor as soon as you start having any side effects, including hot flashes, joint pain, blood clots, trouble sleeping, fatigue, or difficulty concentrating. Don’t wait until the symptoms are intolerable and you have to stop taking the medicine. There are steps you can take to ease these side effects, including switching to a different type of hormonal therapy.
For more information, visit the Breastcancer.org pages on Staying on Track With Treatment. You can read about why it’s so important to stick to your treatment plan, as well as ways to manage side effects after radiation, chemotherapy, and hormonal therapy. If you’re taking hormonal therapy after surgery now, stick with it as prescribed. If you’re thinking of stopping early, talk to your doctor first. Together, you can find a solution that is best for you.