This is a prospective、multicenter、non-comparative interventional case series. 800 breast cancer patients who have already received chemotherapy prior to this study will be enrolled in the group, including 400 patients received the anthracyclines followed taxanes chemotherapy, and the other 400 patients who have received regiments containing no taxanes. Three tumor tissue slices of all the enrolled patients will be collected for TOP2α assay. Meanwhile, 10 years followed-up survey will be conducted. The relationship of TOP2α expression and 5- year or 10-year disease free survival(DFS) and overall survival（OS）will be identified in this study.

800 breast cancer patients who have received chemotherapy prior to this study will be enrolled in the group, including 400 patients received the anthracyclines followed taxanes chemotherapy(Epirubicin 90 mg/m2 d1, Cyclophosphamide 600mg/m2 d1，21days/cycle, 4 cycles, followed by Docetaxel 75mg/m2,d1, 21days/cycle, 4 cycles;or paclitaxel：Epirubicin 90 mg/m2 d1 cyclophosphamide 600mg/m2 d1, 21day/cycle, 4 cycles, followed by paclitaxel 80mg/m2, weekly, 12 wks), and the other 400 patients who have received regiments containing no taxanes (FEC：5-FU 600mg/m2 d1,Epirubicin 90mg/m2 d1, Cyclophosphamide 500mg/m2 d1, 21day/cycle, 6 cycles; or EC: Epirubicin 90mg/m2 d1, Cyclophosphamide 500mg/m2 d1,21 day/cycle, 6 cycles).The patients will be enrolled in the groups within one month after chemotherapy.Three tumor tissue slices of all the enrolled patients will be collected for TOP2α assay. Meanwhile, 10 years followed-up survey will be conducted. The relationship of TOP2α expression and 5-year or 10-year disease free survival(DFS) and overall survival（OS）will be identified in this study.

Inclusion Criteria:

For inclusion in the study, subjects must fulfil all of the following criteria:

1. . Signed and dated informed consent indicating that the patient (or legally acceptable representative) has been informed of all the pertinent aspects of the trial prior to enrollment.
2. . Invasive breast cancer confirmed by histology or cytology with the tumor complete resection.
3. . Patients without remote organs metastasis.
4. . The Ages of patients ≥ 18 years and ≤70 years.
5. . Patients with positive axillary lymph nodes, or negative axillary lymph nodes plus one of these conditions: Triple-negative breast cancer, HER- 2(+),Ki-67≥15%.
6. . The values of aspartate aminotransferase(AST),alanine aminotransferase(ALT), alkaline phosphatase(ALP), total bilirubin(TBIL), UREA, CREA were less than 2 times of upper limits of normal at the beginning of aromatase inhibitors（AIs） therapy.
7. . TOP2α is available to be detected in the primary tumour tissue.
8. . Patients received the regimens of anthracyclines followed Taxanes or containing no Taxanes non-dose dense chemotherapy suggested by the guidelines of National Comprehensive Cancer Network （NCCN) 2014.

Exclusion Criteria:

Any of the following is regarded as a criterion for exclusion from the study:

1. . Patients is in the period of pregnancy or lactation.
2. . Bilateral breast cancer, inflammatory breast cancer or carcinoma in situ.
3. . Previous received neo-adjuvant therapy, including chemotherapy, radiotherapy or endocrinotherapy.
4. . Presence of other life-threatening cancers.
5. . Any severe concomitant condition: uncontrolled cardiac disease or uncontrolled diabetes mellitus. et al.

800 breast cancer patients who have already received chemotherapy prior to this study will be enrolled in the group, including 400 patients who have received the anthracyclines followed taxanes chemotherapy, and the other 400 patients have received regiments containing no taxanes.