Overview
The Oncotype DX Colon Cancer Assay is a new, gene-based diagnostic test that can help men and women with some types of colon cancer learn more about the biological features of their specific tumor and help indicate how likely it is that a patient’s colon cancer may return in the future (recurrence). Coupled with other pieces of information, the results from the Oncotype DX test can help patients and their doctors make personalized decisions about whether or not to include chemotherapy for colon cancer in their treatment plan.
One of the challenges in treating patients with colon cancer is determining the risk that the disease will return after surgery, and justifying the need for additional post-surgical chemotherapy. Post-surgical chemotherapy is given with the intent to further diminish the chance of colon cancer coming back. The estimation of the chance of colon cancer coming back (risk of cancer recurrence) is one of many important factors to consider in deciding whether a patient with Stage II colon cancer should or should not get chemotherapy after surgery. Oncotype DX provides a new way for assessing the risk of recurrence in Stage II colon cancer, and improves the ability to make an informed and personalized decision for each patient.
The Oncotype DX test evaluates a select 12-gene set taken from an individual’s colon cancer sample - 7 colon cancer genes and 5 reference genes - to see how they are expressed, or how active they are. The results of the test are reported as a quantitative Recurrence Score® result, which is a score between 0 and 100 that correlates with the likelihood of a person’s chances of having the colon cancer return. The report may also provide your MMR status which may help you and your doctor in making treatment decisions. Studies have shown that stage II colon cancer patients with MMR-deficient (MMR-D) tumors have a lower risk of recurrence compared to patients with MMR-proficient (MMR-P) tumors.
The Oncotype DX colon cancer test arms the physician with an additional tool in evaluating the needs of the individual colon cancer patient in addition to looking at the individual’s clinical and pathologic characteristics, so that the physician and the patient are in a better position to make the best individualized colon cancer treatment decision.
When Should the Oncotype DX Test Be Used?
The Oncotype DX test should be performed after surgery (resection), but before you and your doctor make a final decision regarding adjuvant chemotherapy treatment (see figure below).
The Oncotype DX test is a non-invasive test that is performed on a small amount of the tissue removed during your original colon cancer surgery or biopsy. This means you should not have to undergo any additional invasive procedures for the test to be performed.
After your surgical procedure, a tissue sample is preserved for further diagnostic testing. If the Oncotype DX test is ordered, the pathologist will send several thin sections of the preserved tumor tissue sample to Genomic Health. The Oncotype DX test results are then integrated with other laboratory test results to help you and your doctor formulate a colon cancer treatment plan based on the unique characteristics of your tumor.
How Was the Oncotype DX Colon Cancer Test Developed?
The Oncotype DX test was developed by a company called Genomic Health. There were 3 main steps in this development process:
- Studying colon cancer genes. First, studies were performed to identify a large number of genes associated with colon cancer. Genomic Health performed its own studies in this area and also relied on the extensive databases developed as part of the Human Genome Project, as well as other sources in the scientific literature. Many of these studies were conducted using research tools called microarrays, which are capable of performing whole-genome analyses of tissue samples and determining whether specific colon cancer genes are expressed.
- Clinical Studies. Once highly relevant groups of colon cancer genes were selected, Genomic Health performed clinical trials with leading oncology centers to explore the correlation of gene expression (using the identified genes) with likelihood of colon cancer recurrence. Applying their proprietary technology, Genomic Health conducted studies looking at the gene expression profile of each individual colon cancer tumor. They then compared each genomic profile with the patient's clinical outcome to see whether or not colon cancer recurred, thus determining which specific colon cancer genes are most significantly correlated with the risk of cancer recurrence.
- A test for determining recurrence. After analyzing samples from more than 1800 patients in these clinical studies, scientists at Genomic Health selected a specific set of genes and developed a mathematical calculation that could help determine the likelihood of recurrence with precision. This formula results in one number, the Recurrence Score result. The gene expression analysis technology and the formula are the two key components of the Oncotype DX test. To verify its accuracy, the Oncotype DX test was validated in an additional, large clinical study involving over 1400 colon cancer patients. This rigorous process resulted in a test which is standardized, reproducible, and based on a wealth of scientific data, thus ensuring that the Oncotype DX test provides valuable information to the healthcare provider.
*At this time, we are unable to perform MMR testing for patients residing in the state of Florida. Please contact Customer Service at +1 (866) ONCOTYPE for further information.