Study Comparing 4 Cycles With 6 Cycles of TC (Docetaxel+Cyclophosphamide) Adjuvant Chemotherapy for 1-3 Lymph Node Positive ER+/HER2- Early Breast Cancer

Inclusion Criteria:

1. women aged 18-70 years old;
2. Patient has localized invasive breast carcinoma with1-3 positive lymph nodes, and isER+/HER2- confirmed by histopathology after early breast cancer surgery（HER2-negativebreast cancer (based on most recently analyzed biopsy) defined as a negative in situhybridization test or an Immunohistochemistry (IHC) status of 0, 1+ or 2+. If IHC is 2+, a negative in situ hybridization (Fluorescence in situ hybridization (FISH),Chromogenic in situ hybridization (CISH) , or Silver in situ hybridization (SISH))test is required by local laboratory testing.), with at least one of the followingconditions: (1) histological grade III; (2) Ki67 ≥ 30%; (3) progesterone receptor (PR) ≤ 20% positive; (4) age less than 35 years; (5) extensive vascular tumor thrombus; (6)multigene detection recurrence score (RS) >25;
3. Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1;
4. Has adequate organ function meeting the following criteria: (1) adequate bone marrowfunction: hemoglobin ≥ 90 g/L (no blood transfusion within 14 days); absoluteneutrophil count ≥ 1.5 x 109 /L; platelet count ≥ 100 * 109 /L; (2)adequate liver andkidney function: Alanine Aminotransferase (ALT) ≤ 3×upper limit of normal (ULN),Aspartate Aminotransferase (AST) ≤ 3×ULN, Total Bilirubin (TBIL)≤ 1.5×ULN, serumcreatinine ≤ 1×ULN，and with endogenous creatinine clearance rate of >50 ml/min (Cockcroft-Gault formula).
5. Participants voluntarily joined the study, has signed informed consent before anytrial related activities are conducted, has good compliance and has agreed tofollow-up.

Exclusion Criteria:

1. Has received neoadjuvant therapy (include chemotherapy, targeted therapy, radiotherapyor endocrine therapy）;
2. Has bilateral breast cancer;
3. Has previous history of additional malignancy, with the exception of adequatelytreated basal cell carcinoma and cervical carcinoma in situ.
4. Has metastatic (Stage 4) breast cancer;
5. Has any >T4 lesion (UICC1987) (with skin involvement, mass adhesion and fixation, andinflammatory breast cancer);
6. Is pregnant, is breast feeding women, or women of childbearing age who cannot practiceeffective contraceptives;
7. Patients participating in other clinical trials at the same time;
8. Has severe organ dysfunction (cardiopulmonary liver and kidney) insufficiency, leftventricular ejection fraction (LVEF) < 50% (cardiac ultrasound); severe cardiocerebral vascular disease within the 6 months previous of randomization (such asunstable angina, chronic heart failure, uncontrolled hypertension with bloodpressure>150/90mmgh, myocardial infarction, or cerebral blood vessel); diabeticpatients with poor blood glucose control; patients with severe hypertension;
9. Has known allergy to taxane and excipients.
10. Has severe or uncontrolled infection;
11. Has a history of psychotropic substance abuse and were unable to abandon drug habits,or those with history of mental disorders;
12. the researchers judged patients to be unsuitable for the study.