The 21-gene test (Oncotype DX®), a genetic screening test for breast cancer, can provide insight into the course of the disease. The purpose of this test is to avoid exposing low-risk patients to the side effects of chemotherapy. According to tumor biology, it can be recommended for patients with positive hormone receptors, no axillary spread and negative HER2. This test, in which cancer-specific 16 gene analysis and 5 reference gene analysis are evaluated together in tumor tissue, reveals the possibility of recurrence. Chemotherapy may not be given to patients with low-risk test results. In patients with high results, it would be appropriate to give chemotherapy in order not to put the patient at risk.
