Selective Avoidance of Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy In HER-2 Positive/Triple Negative Breast Cancer Patients With Excellent Radiologic Response to the Breast and Axilla, Prospective, Multi-center, Single-arm (ASLAN) Study

Inclusion criteria

1. 20≤Age\<70
2. undergone neoadjuvant chemotherapy
3. HER-2 or triple negative breast cancer
4. clinical stage T1-3, N0-1, M0 (AJCC 8th)
5. not Inflammatory breast cancer
6. neoadjuvant chemotherapy should be done before surgery(sandwich method is not allowed)

   * least four times anthacycline or taxane-based regimens
   * no axilla lesion progression during chemotherapy
   * no period of adverse response during chemotherapy
7. undergone anti HER-2 therapy in HER-2 positive patient
8. no preoperative anti hormonal therapy
9. no preoperative radiation therapy
10. did not axillary lymph node biopsy before neoadjuvant chemotherapy
11. physical examination expected complete remission. And radiological expected Tumor size ≤ 2cm or non-mass enhancement ≤ 4cm
12. no previous axilla surgery
13. no previous ipsilateral breast surgery for invasive cancer
14. no Pregnancy-associated breast cancer
15. ECOG performance status 0-1
16. Serum or urine b-HCG negative
17. agree to the consent form

Exclusion criteria

1. During pregnancy
2. major depression or taking psychiatric medication
3. significant psychiatric disorder or history of taking antipsychotic drugs
4. any other lymph node metastasis than axillary lesion
5. undergoing total mastectomy
6. do not agree to the consent form