According to the results of a study that will be presented at the 2009 annual meeting of the American Society of Clinical Oncology (ASCO), the Oncotype DX colon cancer test estimates 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 test 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 test—a gene expression test similar to the Oncotype DX breast cancer test—may allow for more accurate identification of these higher-risk patients.
The 18 genes that are included in the Oncotype DX colon cancer test were selected from among 761 candidate genes that were tested in more than 1,800 patients with Stage II colon cancer. After development, the test was further tested in more than 1,400 additional patients. The results indicate that the Oncotype DXcolon cancer test predicted risk of recurrence after surgery for Stage II colon cancer and provided information beyond that of standard markers of risk.
Reference: 2009 ASCO Annual Meeting May 14 Presscast. Kerr D et al. A quantitative multigene RT-PCR assay for prediction of recurrence in stage II colon cancer: Selection of the genes in four large studies and results of the independent, prospectively designed QUASAR validation study. Abstract #4000.
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