Maintenance Treatment With Eribulin Mesylate Versus Observation in Triple Negative Breast Cancer Patients

Inclusion Criteria: * The patient volunteers and signs an informed consent form; * Age ≥18 years old, female; * The patient was diagnosed as triple-negative breast cancer by histopathology (ER negative (IHC ER positive percentage \<1%), PR negative (IHC PR positive percentage \<1%), HER2 negative (IHC-/+ or IHC++ but FISH/CISH- )), and there is no evidence of metastasis; * Patients underwent radical or breast conserving surgery combined with sentinel lymph node biopsy for primary breast cancer. Margins free of disease and ductal carcinoma in-situ (DCIS) are required. Lobular carcinoma is not considered a positive margin. * For patients who have previously received neoadjuvant therapy for triple-negative breast cancer containing anthracyclines and taxanes, the postoperative efficacy evaluation did not reach pathological complete remission (non-PCR), that is, the primary breast and/or metastatic regional lymph nodes still have histological evidence of malignant tumors other than carcinoma in situ; * For patients who have not received neoadjuvant therapy for triple-negative breast cancer, ≥1 ipsilateral axillary lymph nodes have pathological tumor involvement after surgery. Or the patient's postoperative lymph nodes are negative, but at least meet one of the following conditions: 1. Primary invasive tumor size\> 2cm in pathology; 2. Ki-67 index of untreated breast tissue\>30%; 3. The comprehensive score is at least 8 points (Elston and Ellis 1991) according to the improved Bloom-Richardson grading system (also known as the Nottingham scale), which belongs to the 3rd level; * Physical condition ECOG PS: 0-1; * Previously received adjuvant chemotherapy consisting of a minimum of 6 courses with anthracyclines combined taxanes; * Time window between end of adjuvant chemotherapy and study randomization must be less than 8 weeks. In patients receiving adjuvant radiotherapy, time window allowed between last session and randomisation is 4 weeks; * Laboratory tests meet the following criteria: 1. Bone marrow function: absolute count of blood neutrophils (ANC) ≥1.5×109/L; platelet (PLT)≥100×109/L; hemoglobin (HB)≥90g/L; 2. Liver function: serum total bilirubin (STB), combined bilirubin (CB) ≤ upper limit of normal (ULN) \*1.5; alanine aminotransferase (ALT), aspartate aminotransferase (AST) ≤ULN\*2.5; 3. Renal function: serum creatinine (Cr) ≤ ULN; endogenous creatinine clearance (Ccr) ≥ 60 ml / min (calculated using the Cockcroft-Gault formula). Exclusion Criteria: * Patients with metastatic breast cancer (including contralateral axillary lymph nodes), inflammatory carcinomas; * Previous breast cancer history (except for ipsilateral DCIS that only received local treatment ≥5 years ago), malignant tumors of other histological origins (except for non-melanoma skin cancer or cervical carcinoma in situ) unless the patient's tumor had been completely alleviated and had not received treatment for at least 5 years before the enrollment date; * Major surgery within 4 weeks prior to enrollment, or surgical wounds have not healed; * Embolization and bleeding occurred within 4 weeks before enrollment; * Severe cardiovascular disease, including hypertension (BP≥160/95mmHg) uncontrolled by medical treatment, unstable angina, history of myocardial infarction in the past 6 months, congestive heart failure\>NYHA II, severe heart rhythm Abnormalities and pericardial effusions; * Severe infection requires intravenous antibiotic, antifungal or antiviral treatment; * Suffering from mental illness, poor compliance; * Researchers believe that it is not suitable for inclusion.