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Breast Cancer Study Supports Predictive Value of Oncotype DX Test for Low-Risk Patients

NEW YORK (GenomeWeb) – Researchers from Genomic Health, the National Cancer Institute, and the Surveillance, Epidemiology, and End Results program have published the results of a prospective study in more than 40,000 breast cancer patients showing that Genomic Health's Oncotype DX test could identify patients at low risk for disease recurrence.

In the study, reported this week in Nature Partner Journals Breast Cancer, researchers used Oncotype Dx to analyze breast cancer patients who were involved in one of 14 population-based registries that are part of SEER, testing whether a recurrence score of less than 18 accurately predicted patient survival.

In a statement, Steven Shak, chief scientific officer at Genomic Health, said that the results were "consistent with the clinical validation studies, and confirm and extend the outcomes results from three other recent studies: TAILORx, Clalit Health Services, and PlanB." He added that the Oncotype DX test should now "be recommended and used as standard-of-care in node-negative disease and in certain patients with node-positive disease."

The firm has also previously used the SEER database to assess its Oncotype DX test and track chemotherapy usage in Medicare patients.

In the recent study, from SEER's database of over 370,000 breast cancer patients, the researchers first evaluated 38,568 women between the ages of 40 and 84 years who had been diagnosed with breast cancer between 2004 and 2011 with node-negative, HR+, HER2- disease.

Testing with Oncotype DX, which analyzes expression of 21 genes and assigns a risk of recurrence score based on the results, revealed that just over half of the patients had a recurrence score of less than 18, 38 percent had an intermediate score between 18 and 30, and 8 percent of patients had a score of 31 or higher. Five-year breast cancer-specific mortality was determined to be 0.4 percent, 1.4 percent, and 4.4 percent for the three groups of patients, respectively.

In addition, physicians indicated they treated with chemotherapy 7 percent, 34 percent, and 69 percent of the patients in each risk group, respectively.

Next, the group evaluated another 4,691 patients from the SEER registry who had node-positive lymph nodes. Of that group, 57 percent had a score of less than 18, 36 percent had a score between 18 and 30, and 7 percent had scores of 31 or higher.

The five-year breast cancer-specific mortalities for those groups were 1.0 percent, 2.3 percent, and 14.3 percent for the low-, intermediate-, and high-scored groups, respectively. In addition, physicians reported using chemotherapy in 23 percent, 47 percent, and 75 percent of patients, respectively.

The recurrence score was "significantly prognostic" for five-year breast cancer-specific mortality, the study authors wrote, "independent of patient age, tumor size, and tumor grade."

In addition, Lynne Penberthy, associate director of SEER, said in a statement that the results "demonstrate the potential of future data linkages to enhance the quality, completeness, and usefulness of the SEER data in supporting cancer research and our broadening understanding of the disease."

The authors wrote that they plan to continue to follow the SEER registries, perform more in-depth analyses of various patient subgroups, and assess factors that influence uptake of the test.

The study was supported by the NCI and institutional funds from the Karmanos Cancer Institute and Wayne State University Comprehensive Cancer Center. Genomic Health electronically submitted the test results but did not provide funding for the study.