Capecitabine Maintenance Therapy Following Capecitabine Combined With Docetaxel in Treatment of mBC

Inclusion Criteria:

* Signed informed consent obtained prior to initiation of any study-specific procedures or treatment as confirmation of the patient's awareness and willingness to comply with the study requirements.
* Female patients aged ≥ 18 years.
* Histologically confirmed and documented HER2-negative metastatic breast cancer.
* Previously untreated first-line chemotherapy.
* Patients with at least one measurable lesion according to RECIST criteria at study entry.
* Documented ER/PgR status.
* Prior hormone therapy for metastatic disease is allowed but must stop before study entry.
* KPS\>70.
* Life expectancy of ≥12 weeks

Exclusion Criteria:

* Previous chemotherapy for metastatic breast cancer.
* Prior adjuvant/neoadjuvant chemotherapy within 6 months prior to first study treatment administration.
* Prior (radical)radiotherapy for the treatment of metastatic disease or major surgical procedure within 28 days prior to the first study treatment,
* Inadequate bone marrow function: absolute neutrophil count (ANC): \<1.5 x 109/L, platelet count\<75 x 109/L or hemoglobin \<100g/L.
* Inadequate liver or renal function, defined as:

  1. Serum (total) bilirubin \>2 x the upper limit of normal (ULN) for the institution
  2. AST/SGOT or ALT/SGPT \>2.5 x ULN (\>5 x ULN in patients with liver metastases)
  3. ALP \>2.5 x ULN at baseline (\>5 x ULN in patients with liver metastases).
  4. Serum creatinine\>140umol/L.
* Pregnant or lactating females.
* Her-2 positive (ICH +++ or FISH positive).
* Symptomatic cerebral parenchyma and/or leptomeningeal metastases.
* Other malignancy within the last 5 years, except for adequately treated carcinoma in situ of the cervix or squamous carcinoma of the skin, or adequately controlled limited basal cell skin cancer.
* Pre-existing peripheral neuropathy ≥grade 1 according NCI CTCAE 4.0.
* Mental disease or other conditions affecting on the compliance of patients.
* Other serious disease or medical condition:

  1. History of uncontrolled seizures, CNS disorders or psychiatric disability judged by the Investigator to be clinically significant precluding informed consent.
  2. Congestive heart failure, or unstable angina, myocardial infarction within ≤6 months prior to the first study treatment, uncontrolled hypertension and high risk, uncontrolled arrhythmias.
  3. Uncontrolled acute infection
* Inability to take or absorption oral medications.
* Concurrent or within 30 days using drugs of other clinical trials.
* Previous treatments containing Capecitabine (whether adjuvant or palliative treatment).
* Previous treatments containing docetaxel within 12 months.
* Known hypersensitivity to any of the study treatments or excipients.
* Any other conditions the research consider not appropriate to take part in the trial.