OncotypeDX® Colon Cancer Assay | oncotest

OncotypeDX® Colon Cancer Assay

Relating to cancer treatment:

Colon cancer

Target patients:

Patients (men and women) diagnosed with colon cancer at stage 2 or 3 of the disease after an operation for tumor resection

Test description:

Assessment of risk of recurrence and help your doctor make a more informed, individualized treatment decision

Type of sample:

A sample of tumor tissue that is taken during an operation and is paraffin embedded

Additional information

Colon cancer is a disease that is treated using a very wide range of measures: surgery for removal of the primary tumor in the intestine, an option for operations for removing metastases of the tumor from the live and other organs, chemotherapy in various combinations of chemical drugs and treatments combining various biological drugs too. For each patient, the attending physician must select the best options – those that will provide the patient the maximum benefit alongside the minimal damage concomitant to chemotherapy.

Because the most basic treatment of the disease is surgery for removal of the primary tumor, the attending physician must decide which patients would gain benefit from administering adjuvant chemotherapy. In some patients, it is clear that the patient is superfluous (in cases in which the penetration of the tumor into the intestine tissue is minimal, stage 1 patients), while in some patients it is obvious that treatment must be given to stop the progress of distant metastases or when the tumor tissue has penetrated relative to the depth of the intestine tissue (patients classified as stage 3 or 4). The patients for whom there is doubt concerning the balance of benefit and damage from chemotherapy are patients in the intermediate group – the patients who are classified as stage 2: those whose disease has penetrated moderately into the intestinal tissue and has not sent distant metastases.

For many years, the policy for treating stage 2 colon cancer patients after an operation was controversial. The main problem was due to the fact that it was difficult to assess the degree of risk of these patients for recurrence of the disease in the future. Most of the problem for which adjuvant therapy is administered is prevention of disease recurrence, so for patients whose risk of recurrence was low, administering chemotherapy poses an unnecessary risk.

A similar dilemma existed until a few years ago in the treatment of breast cancer too. However, for several years, a test called Oncotype has been performed on breast cancer tissue. This test examines a group of genetic changes in tumor cells as it has been found that these changes constitute a reliable index that predicts the degree of risk of disease recurrence. Indeed, today, the Oncotype test constitutes part of the routine course of therapeutic decision making in cases of early breast cancer.

Similarly, a set of genes that may be tested in colon cancer cells has been defined and diagnosed. It turns out that changes in these genes have high correlation to the degree of risk of disease recurrence. Today, the test can be performed in the tumor tissue that is excised during the primary operation and the degree of risk of disease recurrence can be defined – when it is high, the attending physician will recommend administering adjuvant chemotherapy for preventing recurrence. In cases in which the degree of risk for disease recurrence is low, it is likely that the attending physician will recommend avoiding this treatment.

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