Genomic testing helps individualize treatment. This means that patients with more serious conditions can be identified and offered aggressive and innovative therapies that may prolong their lives, while patients who are diagnosed with a less serious condition may be spared unnecessary treatments. Genomics generally refers to the study of the study of the entire genome (all of the DNA in an organism). Genomics can consider multiple genes and how they interact with each other and the environment to affect health.
Cancer is the result of genetic abnormalities that affect the function of particular genes. Genes determine the form, function, and growth patterns of cells. Those that accelerate or suppress growth are often involved in cancer. For example, many cancers have an abnormality in a gene that is responsible for stimulating cellular growth and/or the gene that normally prevents cancer is not working properly. Both of these genetic abnormalities can result in uncontrolled and excessive cellular growth, the hallmark trait of cancer. Genomic tests, or assays as they are called by scientists, are a tool for identifying the specific genes in a cancer that are abnormal or are not working properly. In essence, this is like identifying the genetic signature or fingerprint of a particular cancer.
Genomic testing is different from genetic testing. Genetic tests are typically used to determine whether a healthy individual has an inherited trait (gene) that predisposes them to developing cancer. Genomic tests evaluate the genes in a sample of diseased tissue from a patient who has already been diagnosed with cancer. In this way, genes that have mutated, or have developed abnormal functions, are identified in addition to those that may have been inherited.
A newer test that may help guide treatment decisions for patients with Early Stage colon cancer is OncotypeDX colon cancer test. The Oncotype DX® Colon Cancer Test—measures the aggressiveness of colon cancer. The Oncotype DX colon cancer test evaluates 12 genes in a sample of tumor tissue and generates a Recurrence Score. The Recurrence Score provides information about the likelihood of cancer recurrence—and as a result, can improve treatment decisions.
This test—which is similar to a test that is commonly used for patients with early-stage breast cancer—is performed after surgery but before final decisions are made about adjuvant (post-surgery) therapy. The test estimates the risk of cancer recurrence by evaluating the activity of certain genes in a sample of tumor tissue.1 Risk of recurrence can vary greatly among patients with Stage II colon cancer, and use of this genomic test in combination with other markers of risk may help to individualize treatment decisions. Adjuvant (post-surgery) chemotherapy is not routinely recommended for all patients with Stage II colon cancer, but may be considered for high-risk patients.
1 Benson AB, Schrag D, Somerfield MR. American Society of Clinical Oncology recommendations on adjuvant chemotherapy for stage II colon cancer. Journal of Clinical Oncology. 2004;15:3408-19.