This test is performed on tissue from the initial biopsy or lumpectomy specimen. It uses the unique genetic profile of each woman’s breast cancer to make an accurate prediction about whether the cancer will recur. It measures an array of genes that are known to be associated with more aggressive tumors. The test has been shown to be much more powerful than current predictive methods, which are based on “clinical staging”, which is based on the size of the tumor and the status of the lymph nodes