Positive results from international study of Oncotype DX breast cancer RS

Mar 9 2010

Genomic Health, Inc. (Nasdaq: GHDX) today announced the publication of positive results from a large international study which demonstrated that the Oncotype DX® breast cancer Recurrence Score® (RS) result is a significant independent predictor of distant recurrence in both node-negative and node-positive, hormone receptor-positive, postmenopausal breast cancer patients who are treated with either anastrozole or tamoxifen. The study, originally presented at the San Antonio Breast Cancer Symposium in 2008, was published online today in the Journal of Clinical Oncology.  

The Oncotype DX breast cancer test measures the expression of 21 genes of an individual tumor to generate an RS result that quantifies the magnitude of chemotherapy benefit and the likelihood of recurrence for early-stage breast cancer patients.  As of December 2009, more than 8,000 physicians had used more than 135,000 Oncotype DX breast cancer tests for treatment planning.

"We believe the results of this study reinforce the important role of Oncotype DX in making individualized treatment decisions for early stage breast cancer patients with node-negative and node-positive disease," said Steven Shak, M.D., chief medical officer of Genomic Health.  "Oncotype DX testing allows physicians and patients to make a more informed decision on whether to add chemotherapy, yielding a potential savings to the U.S. healthcare system of approximately $2,000 in direct costs per patient."

The study used Oncotype DX to analyze tumor samples from 1,231 patients involved in the landmark ATAC (Arimidex®, Tamoxifen, Alone or in Combination) trial, which established the extensive use of aromatase inhibitors for adjuvant treatment of postmenopausal women with hormone receptor-positive breast cancer. Nine-year distant recurrence was assessed for women in the anastrozole and tamoxifen monotherapy arms of the ATAC trial, including patients with disease that had spread to the lymph nodes (0 nodes, 1-3 nodes and 4 or more nodes).

Researchers collected tumor blocks primarily from patients in the United Kingdom and tested the significance of adding the RS result to a clinical model consisting of age, tumor size, grade and treatment, as well Adjuvant! Online, a valid risk assessment tool that evaluates clinical variables to help physicians and patients assess the risks and benefits of getting additional therapy after surgery.

Results indicated that the RS result provided statistically significant prognostic value beyond that provided by Adjuvant! Online in node-negative (p<0.001) patients. While the study confirmed the performance of the RS result in a large contemporary patient population of postmenopausal hormone receptor-positive women treated with tamoxifen, it also demonstrated that the established relationship between the RS and risk of distant recurrence for tamoxifen may now be applied to anastrozole. The greater efficacy of anastrozole observed in the parent ATAC trial and the analysis of the RS results in both treatment arms from this study suggests a lower risk of recurrence in patients treated with aromatase inhibitors. Additionally, as consistent with prior OncotypeDX results in node-positive breast cancer, for any RS result, the likelihood of distant recurrence increases with the number of positive nodes.

SOURCE Genomic Health