Inclusion Criteria:  Age ≥ 18 years old, ≤ 70 years old. Eastern Cooperative Oncology Group (ECOG) ≤ 2. Postoperative pathology is clearly diagnosed as invasive breast cancer. Estrogen receptor (ER) or progesterone receptor (PR) positive, HER2 negative. Available with Formalin-Fixed and Parrffin-Embedded (FFPE) tumor tissue. Stage I-II patients who have received surgery (breast-conserving or mastectomy) and the pathological staging is pT1-2N0-1M0 or pT3N0M0. The patient had not received systemic systemic treatment (including radiotherapy, chemotherapy, immunotherapy, endocrine therapy) before enrollment. Signed an informed consent form.  Exclusion Criteria:  Breast cancer patients whose clinical or pathological stage is T4, N2-3 or M1. Known human immunodeficiency virus infection (HIV) or acquired immunodeficiency syndrome (AIDS) related diseases. Other psychiatric disorders that may interfere with the judgment of the study results, or abnormal laboratory tests; and who, in the judgment of the investigator, are considered unfit to participate in the study. Patients with double breast cancer. Severe/uncontrolled intercurrent diseases/infections. Subjects with allogeneic organ transplants requiring immunosuppressive therapy. Hormone receptors ER and PR are negative (any detectable estrogen and progesterone receptors do not express or express <1%) and/or HER2 overexpression/amplified by FISH detection. Not suitable for hormone receptor modulators (e.g. tamoxifen) and adjuvant endocrine other drug therapy.