Genomic Health, Inc. (Nasdaq: GHDX) today announced results from two studies demonstrating that quantitative reporting for HER2 gene expression, as measured by the company's Oncotype DX(R) breast cancer assay, has a high degree of concordance with both fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) testing. HER2 is an important marker for therapeutic decision-making for patients with breast cancer, and its measurement significantly impacts the chosen course of treatment. The research was presented at the ASCO Breast Cancer Symposium, September 5-8, 2008, in Washington, D.C.

"Many clinicians who already rely on the Recurrence Score(R) result for treatment planning have specifically requested that we provide the quantitative measure of HER2 gene expression in Oncotype DX reports," said Steven Shak, M.D., chief medical officer of Genomic Health. "Based on this research demonstrating the accuracy and reliability of HER2 measurement using RT-PCR, Oncotype DX can provide additional patient-specific information and insight into each patient's individual tumor biology."

Oncotype DX uses reverse transcription-polymerase chain reaction (RT-PCR) technology to quantify gene expression of 21 genes, one of which is HER2. The two studies found high concordance for testing with Oncotype DX compared to FISH (97 percent) and IHC (95 percent). Earlier this year, Genomic Health increased the clinical utility of Oncotype DX by providing single gene reporting for the expression of estrogen and progesterone receptors. The company expects to further increase the clinical utility of its test by including single gene reporting for quantitative HER2 gene expression in all Oncotype DX reports by the end of 2008.

The first study (Abstract 13), conducted by Genomic Health and collaborators from the Eastern Cooperative Oncology Group and sanofi-aventis, demonstrated a high degree of overall concordance -- 95 percent -- between central IHC and quantitative RT-PCR using Oncotype DX for determining HER2 status. The study analyzed 755 patients with 0 to 3 positive lymph nodes who were enrolled in Intergroup study E2197, a large adjuvant breast cancer trial evaluating two different chemotherapy regimens.

The second study (Abstract 41) found a high degree of concordance -- 97 percent -- between RT-PCR using Oncotype DX and central laboratory FISH assessment of HER2 status. The study was conducted by Genomic Health and collaborators from Kaiser Permanente; the University of California, San Francisco; and PhenoPath, Inc. HER2 measurement was assessed by central FISH and quantitative RT-PCR using Oncotype DX in 568 patients from a large Kaiser Permanente case-control study (Habel et al., Breast Can Res 2006). As previously reported, this study also found a significantly greater risk of breast cancer death in patients who were determined to be HER2-positive by Oncotype DX. Since patients in both these studies did not have the option of Trastuzumab treatment, the direct relationship between HER2 and Trastuzumab treatment response could not be assessed.

"During tumor sample preparation for IHC or FISH analysis, variability in the preanalytic process may lead to differences in results and interpretation, and, consequently, to potentially inappropriate treatment decisions," said Frederick L. Baehner, M.D., Senior Pathologist at Genomic Health and lead author of both studies. "Oncotype DX's RT-PCR technology for HER2 gene expression employs a large number of controls, which are intended to safeguard against variability in order to ensure a reproducible quantitative result."

Results from an unrelated breast cancer study to evaluate whether new genes, including TOPO2A, might complement the Recurrence Score result and identify individuals more likely to selectively benefit from taxanes were also presented during the ASCO Breast Cancer Symposium.

About Oncotype DX(R)

Oncotype DX is the first and only multi-gene expression test commercially available that has clinical evidence validating its ability to predict the likelihood of chemotherapy benefit as well as recurrence in early-stage breast cancer. Additionally, the test report provides quantitative scores for certain individual genes. Oncotype DX has been extensively evaluated in multiple independent studies involving nearly 4,000 breast cancer patients, including a large validation study published in The New England Journal of Medicine and a chemotherapy benefit study published in the Journal of Clinical Oncology. To date, 7,500 physicians have ordered more than 65,000 tests, and health plans covering over 80 percent of U.S. insured lives provide reimbursement for Oncotype DX through contracts, agreements and policy decisions. Both the American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network recommend the use of Oncotype DX for patients with node-negative breast cancer that is estrogen-receptor positive and/or progesterone-receptor positive. For more information about Oncotype DX, please visit .

About Genomic Health

Genomic Health, Inc. (Nasdaq: GHDX) is a life science company focused on the development and commercialization of genomic-based clinical laboratory services for cancer that allow physicians and patients to make individualized treatment decisions. In 2004, Genomic Health launched its first test, Oncotype DX(R), which has been shown to predict the likelihood of breast cancer recurrence and the likelihood of chemotherapy benefit in a large portion of early-stage breast cancer patients. The company was founded in 2000 and is located in Redwood City, California. For more information, please visit .

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including statements relating to the company's belief that including HER2 measurement in its test results can provide additional insight into patients' individual tumor biology, the company's expectations regarding timing of inclusion of HER2 results in Oncotype DX reports, and the belief that the company's technology for measuring HER2 gene expression is intended safeguard against preanalytic variability in order to ensure a reproducible quantitative measure of HER2. These risks and uncertainties include, but are not limited to: the results of additional clinical studies; the applicability of clinical study results to actual outcomes; the risk that we may not obtain sufficient levels of reimbursement for any future tests we may develop; our ability to develop and commercialize new products; the risks and uncertainties associated with the regulation of our tests by FDA; our ability to obtain capital when needed; our history of operating losses and the other risks set forth in our filings with the Securities and Exchange Commission, including the risks set forth in our Quarterly Report on Form 10-Q for the three-month period ended June 30, 2008. These forward-looking statements speak only as of the date hereof. Genomic Health disclaims any obligation to update these forward- looking statements.

NOTE: The Genomic Health logo, Oncotype, Oncotype DX and Recurrence Score are trademarks or registered trademarks of Genomic Health, Inc. All other trademarks and service marks are the property of their respective owners.