The primary aim of this prospective, multicentre study is to determine whether the involved node can be marked using black carbon dye and successfully identified at the time of surgery. The secondary aims are to determine the concordance between the tattooed node and sentinel node, migration of black dye into other nodes, and false-negative rate of tattooed node (in patients undergoing ALND after NACT).

Pretreatment evaluation of axillary lymph nodes and marking of biopsied nodes in patients with newly diagnosed breast cancer is becoming routine practice. Tagging of biopsied axillary lymph nodes with metal markers, similar to what is done for suspicious breast lesions, is being adopted in clinical practice. The need to mark a positive axillary lymph node becomes especially relevant in cases where neoadjuvant chemotherapy (NACT) is anticipated so that these nodes may be identified at the time of surgery. Measures that improve both the accuracy of nodal evaluation after NACT and the ability to assess treatment response are desirable in order to tailor therapies for breast cancer treatment. The investigators sought to test tattooing of biopsied axillary lymph nodes with a sterile black carbon suspension.

Inclusion Criteria:

1. Female; 2. Aged >=18 years; 3. With invasive breast cancer; 4. Patients to be treated with neoadjuvant chemotherapy; 5. Patients scheduled to undergo routine fine needle aspiration (FNA) or core biopsy of abnormal axillary lymph node; 6. Patients with operable breast cancer; 7. Heart, lung, liver and kidney function well, suitable for patients undergoing surgery; 8. Informed consent patients.

Exclusion Criteria:

• 1. Patients who do not plan or are unable to operate; 2. Patients with distant metastasis were excluded; 3. Patients without invasive cancer components in DCIS alone; 4. Patients who are unable to cooperate with the doctor's recommended surgical treatment (breast conserving surgery or radical surgery) due to personal or family factors; 5. Patients with serious cardiopulmonary diseases, uncontrolled infectious diseases and other non tumor related diseases who can not tolerate comprehensive treatment such as surgery and chemotherapy; 6. Patients with mental illness or other reasons unable to sign informed consent; 7. Patients with poor medical compliance who cannot complete the trial treatment process and follow-up according to the standard according to the researcher's opinion.