The aims of this study is to evaluate 5 year recurrence free survival when omit sentinel lymph node biopsy after neoadjuvant chemotherapy in triple negative or HER-2 positive breast cancer patients when physical examination expected complete remission. And radiological expected Tumor size ≤ 2cm or non-mass enhancement ≤ 4cm.

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