Doctors have used a genetic test to decide which patients may be able to skip chemotherapy after surgery for breast cancer for the past 10 years.
A recent study confirms that Oncotype DX, the genetic test, works well for a small group of patients. However, a more extensive follow-up study is needed to draw conclusions for a fuller range of patients with riskier tumors.
Oncotype DX analyzes 21 genes in a tumor in order to estimate a woman’s risk of the cancer coming back after surgery.
99% of patients who fell into the test’s low-risk category didn’t develop metastatic breast cancer five years after surgery even though they didn’t have chemotherapy. According to doctors, the survival rate among patients in the low-risk category was 98%.
230,000 Americans are diagnosed with breast cancer annually. About 100,000 qualify for the Oncotype DX of which 16,000 fall into the low-risk category.
The test costs $4,000 and is covered by most insurers.
In the study, doctors nationwide administered the Oncotype DX test to more than 10,000 women diagnosed with a common form of breast cancer that responds to anti-hormone treatments. 16% of the women scored low on the test and consequently only received anti-hormone therapy and no chemotherapy.
Five years later, this group of women were more likely to either develop another type of cancer or die of something other than cancer than they were to have their first tumors return somewhere else in their bodies.
However, for a large portion of patients the test is still ambiguous. Practically 70% of the patients in the study scored in the mid-range of the test and were considered a moderate risk for a relapse.
Researchers are now testing to see which of these patients benefit from chemotherapy. The results of the trial are anticipated to be published in a few years.