New Genetic Test Predicts Recurrence
New Genetic Test Predicts Recurrence in Women with Node-Negative, Estrogen-Receptor- Positive Breast Cancer
S. Paik et al.
New England Journal of Medicine, December 30, 2004
Background and importance of the study: Choosing treatments for breast cancer can sometimes feel like a balancing act. You want to do everything you can to keep the breast cancer from coming back (recurring). But you don't want to have adjuvant treatments—treatments given after surgery to lower the risk of recurrence - that you really don't need.
Depending on your doctors' assessment of your risk of recurrence, they may recommend chemotherapy, radiation therapy, and the hormonal therapy, tamoxifen.
How do doctors estimate the risk of recurrence in women diagnosed with node-negative, estrogen-receptor-positive breast cancer? They look at a list of breast cancer characteristics, including:
A woman's age, overall health, and life-style history may also affect her risk.
Another way to learn about a particular cancer is to look at its genetic make-up. Several small studies have used genetic material from cancer cells to predict the risk of recurrence. The goal is to develop a reliable test of who would benefit from adjuvant treatments and who will do just fine without them.
In the study reviewed here, researchers looked at a new genetic test, the Oncotype DX, to see how accurately it predicted distant recurrence (the cancer coming back in another place in the body) in women newly diagnosed with node-negative, estrogen-receptor-positive breast cancer. The women had been treated with tamoxifen. They had not received chemotherapy.
Study design: Researchers in the National Surgical Adjuvant Breast and Bowel Project (NSABP) looked at stored breast cancer tissue samples from 668 women who had been diagnosed with node-negative, estrogen-receptor-positive breast cancer and had received tamoxifen. The women had been enrolled in the NSABP B-14 clinical trial from 1982 to 1988. NSABP researchers tracked the women for about 10 years after surgery.
Using the Oncotype DX test, the researchers analyzed the genes in the tissue samples and assigned each sample a "recurrence score":
- less than 18: a low risk of distant recurrence (51% of the women were in this group),
- 18 to 30: a medium risk of distant recurrence (22% of the women were in this group), or
- 31 or higher: a high risk of distant recurrence (27% of the women were in this group).
They then compared the three groups with the medical histories of the women in each group to see how accurately the Oncotype DX test predicted risk of distant recurrence.
The researchers also compared the Oncotype DX test results with recurrence predictions based on other factors:
- age,
- cancer size,
- hormone receptor protein levels,
- HER2 levels, and
- cancer grade.
Results: The researchers found that the Oncotype DX test accurately categorized the women as high, medium, or low risk, when compared to the actual rate of distant recurrence 10 years after surgery:
- 6.8% of the women in the low-risk group had a distant recurrence.
- 14.3% of the women in the medium-risk group had a distant recurrence.
- 30.5% of the women in the high-risk group had a distant recurrence.
The researchers also compared the results of the Oncotype DX test predictions with predictions based on other factors. The test was a significantly better predictor of distant recurrence than:
- age,
- cancer size,
- HER2 levels, and
- hormone receptor protein levels.
The Oncotype DX test and a high cancer grade (meaning the cancer cells do not look at all like normal cells) were about equal in their ability to significantly predict of distant recurrence.
The researchers also found that the Oncotype DX recurrence score significantly predicted overall survival (how many of the women were alive).
Conclusions: The researchers concluded that the Oncotype DX recurrence score was a good predictor of distant recurrence in women with node-negative, estrogen-receptor-positive breast cancer who had been treated with tamoxifen.
Take-home message: In general, women diagnosed with node-negative, estrogen-receptor-positive breast cancer have a very good outlook after surgery, radiation, and tamoxifen. But some will have distant recurrence (when the cancer comes back in another part of the body).
Here's the big question—how do you figure out if you are:
- at high risk for recurrence and are likely to benefit from chemotherapy,
- or at low risk of recurrence and can avoid chemotherapy?
The Oncotype DX test may offer you and your doctor another, very helpful way to predict your risk of cancer recurrence, so that you can make the best treatment decisions. Each woman's situation is different. Your doctor might say that other characteristics of your cancer strongly suggest it will behave well, or not so well.
If you have been diagnosed with a node-negative and hormone-receptor-positive cancer, your situation is already favorable. But if all of the other features of the cancer are also favorable—small tumor size, normal HER2 gene, low cancer grade, and absence of lymphatic-vascular invasion (the cancer is not in the lymph channels or blood vessels of the breast) your risk of recurrence would be low. You'd be likely to do well on hormonal therapy alone and therefore probably don't need chemotherapy.
On the other hand, you and your doctor will be more likely to agree that you need chemotherapy if other factors are unfavorable: medium to large cancer size, abnormal HER2 gene, high cancer grade, and significant lymphatic-vascular invasion.
If you have a mix of favorable and unfavorable features and you're really on the fence about whether to have chemotherapy, you may want to talk to your doctor about the test. Together you can decide if it's right for you.
The Oncotype DX test has been studied ONLY with women who have node-negative, estrogen-receptor-positive breast cancer that has been treated with tamoxifen. The Oncotype DX test is NOT recommended for you if:
- you have any other type or stage of breast cancer, or
- if you've had (or plan to have) another form of hormonal treatment besides tamoxifen (such as an aromatase inhibitor).
Because the Oncotype DX test is so new, many health insurance companies have not yet decided whether or not to cover it. The test costs about $3,500. If you and your doctor decide to use the test, your doctor's office may be able to help you talk to your insurance company. The company that makes the Oncotype DX test, Genomic Health, Inc., provides help too. Their toll-free number is 866-ONCOTYPE (866-662-6897).
Stay tuned to breastcancer.org for the latest updates on this and other new tests that will help ensure the best treatment for YOU.
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