According to a press release from Genomic Health, the Oncotype DX colon cancer assay—a genomic test similar to one already in use for breast cancer—has been shown to predict the risk of cancer recurrence among patients with Stage II colon cancer. This test may eventually help guide colon cancer treatment decisions.
Gene expression profiling explores the patterns of genes that are active in tumor cells. Studies suggest that gene expression may provide important information about prognosis or likely response to treatment in several types of cancer. For example, among women with early-stage, estrogen receptor-positive breast cancer, the Oncotype DX breast cancer assay has been shown to predict the likelihood of cancer recurrence and the likelihood of benefit from chemotherapy. As a result, the test has been added to medical guidelines for early-stage breast cancer. The test 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.
Research now indicates that a similar test may provide important information for patients with Stage II colon cancer. Stage II colon cancer refers to cancer that extends through the wall of the colon but has not invaded lymph nodes or spread to distant parts of the body. Many patients with this stage of disease have good outcomes with surgery alone, and routine adjuvant (post-surgery) chemotherapy is not currently recommended for Stage II colon cancer. Chemotherapy may, however, be considered for Stage II patients with a higher risk of cancer recurrence. Use of the Oncotype DX colon cancer assay—a gene expression test similar to the Oncotype DX breast cancer assay—may allow for more accurate identification of these higher-risk patients.
The genes that are included in the Oncotype DX colon cancer assay were selected from among 760 candidate genes that were tested in more than 1,800 colon cancer patients. After development, the assay was further tested in more than 1,200 patients with Stage II colon cancer. The results indicate that the Oncotype DX colon cancer assay predicted risk of recurrence after surgery for Stage II colon cancer and provided information beyond that of standard markers of risk. Detailed results of this analysis will be presented at the annual meeting of the American Society of Clinical Oncology (ASCO), May 29-June 2, 2009.
Reference: Genomic Health, Inc. Press Release. Genomic Health Announces Positive Preliminary Results from QUASAR Validation Study of Oncotype DX Colon Cancer Assay. Available at: . Accessed April 15, 2009.
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