According to results presented at the 2004 annual San Antonio Breast Cancer Symposium (SABCS) and published in the New England Journal of Medicine, further evidence indicates that Oncotype DX, a new diagnostic test utilizing gene expression, is highly predictive of distant recurrences (cancer spread to distant sites in the body) and even overall survival in women with early, hormone-positive breast cancer that have undergone treatment with tamoxifen. Patients at a high risk of recurrence or death according to results from Oncotype DX may benefit from additional treatment, while patients at a low risk may be spared from unnecessary treatment.
Breast cancer is responsible for approximately 40,000 deaths annually in the United States alone. However, if breast cancer is detected early, prior to the spread of cancer, cure rates remain high. Although patients with early breast cancer derive a significant survival benefit overall with the addition of chemotherapy in their treatment regimen, some women who can be cured with surgery and hormone therapy alone may be exposed unnecessarily to chemotherapy, suffering from side effects caused by the treatment while gaining no benefit. By using a test such as Oncotype DX to determine whether a patient is likely to achieve benefit from chemotherapy and/or is likely to experience a cancer recurrence, physicians can tailor treatment to meet the needs of individual patients.
Oncotype DX is a test that uses breast cancer biopsies, or small tissue samples, to determine whether a patient has breast cancer. The test analyzes the expression of specific genes or clusters of genes of the cancer cells and, through statistical analysis, can provide associations between the expression of one or more genes and specific outcomes of patients, such as risk of a cancer recurrence. Oncotype DX is used to determine the risk of a distant recurrence in women with node-negative, estrogen receptor-positive breast cancer through the evaluation of 21 genes.
Researchers recently conducted a study to evaluate the effectiveness of Oncotype DX in predicting the risk of a cancer recurrence in women with early breast cancer. The study was performed on 668 specimens of cancer from women with hormone-positive, early breast cancer that had undergone treatment with the anti-estrogen agent tamoxifen (Nolvadex®). According to results from Oncotype DX, 51% of women were at a low risk of developing a distant recurrence, 22% of women were at an intermediate risk of developing a distant recurrence, and 27% of women were at a high risk of developing a distant recurrence. At 10 years follow-up, patients in the low-risk category had 6.8% risk of ultimately developing a distant recurrence, patients in the intermediate-risk category had a 14.3% risk of developing a distant recurrence, and patients in the high-risk category had a 30.5% risk of developing a distant recurrence. Furthermore, the risk of a patient developing a distant recurrence according to Oncotype DX correlated with the risk of death in these women, providing further evidence for the relevancy of the test.
The researchers concluded that Oncotype DX can help predict the level of risk for a distant recurrence or death in patients with early, hormone-positive breast cancer who have undergone treatment with tamoxifen. Those patients at a high risk may benefit from additional chemotherapy, while those at a low risk may be spared from chemotherapy and the resulting side effects. Patients with early breast cancer may wish to speak with their physician regarding the risks and benefits of Oncotype DX testing.
Reference: Paik S, Shak S, Tang G, et al. A multigene assay to predict recurrence of tamoxifen-treated, node-negative breast cancer. New England Journal of Medicine. 2004;351:2817-2816.
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