A 21-gene test of a patient's breast cancer tumor may change doctor and patient treatment decisions, including the need for chemotherapy, a new study shows
The test, Oncotype DX, is made by Genomic Health Inc. It examines 21 genes from a tumour sample to determine how active they are.
A test score between 0 and 100 predicts how likely the cancer is to recur. For women with low scores, chemotherapy is not recommended.
More than 120,000 breast cancer patients have undergone the test since it became commercially available in 2004.
The test is intended for patients who have a type of breast cancer, called estrogen receptor-positive, which has not spread to the lymph nodes. About 100,000 such cases are diagnosed each year.
"The trend in oncology is towards personalized medicine. We likely will see more tests similar to this one in the future," said Loyola University Health System Medical oncologist and study's lead author Dr. Shelly Lo.
The findings are based on study, which included 89 breast cancer patients who received the gene test.
They were treated by 17 medical oncologists at Loyola, University of Michigan, University of California at Davis and Edward Hospital in Naperville, Il.
Doctors changed treatment decisions for 28 patients. In 20 of these cases, they changed their decision from hormone therapy plus chemotherapy to hormone therapy alone. 24 patients changed their treatment decisions, including nine who dropped chemotherapy.
"This is the first study to show that results from this test simultaneously impact decisions by physicians as well as patients," Lo said.
The study has been published in the Journal of Clinical Oncology.