Use of the Oncotype DX™ test to estimate the risk of cancer recurrence in women with node-negative, hormone receptor-positive breast cancer can change initial decisions about choice of treatment. These results were presented at the 2007 annual meeting of the American Society of Clinical Oncology (ASCO).

Although chemotherapy is recommended for many women with early-stage, node-negative breast cancer, the benefit of chemotherapy varies. Identifying in advance those women who are most likely to benefit from chemotherapy may allow for more individualized treatment. This would allow women who are unlikely to benefit from chemotherapy to avoid the toxic effects of treatment.

OncotypeDX™ is a genomic test that may be useful in determining which patients with newly diagnosed, Stage I or II, node-negative, estrogen receptor (ER)-positive breast cancer are likely to benefit from adjuvant chemotherapy in addition to hormonal therapy. OncotypeDX™ predicts the risk of a patient experiencing a recurrence 10 years following diagnosis. Oncotype DX™ evaluates the activity of 21 genes from a sample of the patient’s cancer to determine the patient’s Recurrence Score. The Recurrence Score ranges from 0 to 100, with a higher score indicating a greater risk of recurrence.

To explore whether Oncotype DX™ test results influence treatment decisions made by medical oncologists and patients, researchers conducted a study among 89 patients who had been treated by 17 medical oncologists at four different medical facilities.[1]

• In roughly 32% of the cases, the Oncotype DX™ test result changed the oncologist’s choice of treatment. The test results also influenced the patient’s choice of treatment.
• The most common change in treatment plan involved a shift away from chemotherapy and hormonal therapy in favor of hormonal therapy alone.
• The oncologists reported that the Oncotype DX™ test results increased their confidence in the final treatment plan in 76% of the cases.
• 95% of patients were glad they took the test.

These results suggest that Oncotype DX™ test results influence treatment decisions made by oncologists and patients, and increase confidence in the final treatment plan.

In a related study, researchers evaluated whether oncologists were able to predict a patient’s recurrence risk without use of the Oncotype DX™ test.[2] Oncologists accurately identified most high-risk women, but correctly distinguishing low-risk women from intermediate-risk women proved more difficult. Use of the Oncotype DX™ test changed treatment decisions in 19% of the cases.

A clinical trial known as the TAILORx study will further evaluate the use of Oncotype DX in guiding treatment decisions. The study is currently enrolling patients in the U.S. and Canada. For more information, visit http://www.cancer.gov/clinicaltrials/digestpage/TAILORx

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