Inclusion Criteria:  Early stage (I, II or III) female breast cancer patients, who have completed 4-7 years of primary adjuvant endocrine therapy Patient was diagnosed with invasive breast carcinoma (ductal, lobular, or mixed ductal/lobular). The primary tumor was hormone receptor positive (HR+), i.e. estrogen receptor-positive and/or progesterone receptor-positive. The primary tumor was HER2 negative or positive and node-negative or node-positive with 1-3 positive lymph nodes. Subject has pre-treatment breast tumor tissue [formalin fixed and paraffin embedded (FFPE)] from a previous breast-conserving surgery, mastectomy or core needle biopsy available for testing by the Sponsor.  Exclusion Criteria:  Patient has distant metastatic disease (M1). Patient was diagnosed with metaplastic breast cancer, carcinosarcoma, sarcoma, neuroendocrine carcinoma, adenoid cystic carcinoma, or phyllodes tumor.