The Validation of Sentinel Lymph Node Biopsy After Neo-adjuvant Chemotherapy in Breast Cancer Patients

Neoadjuvant or primary systemic treatment is increasingly applied in the treatment of operable breast cancer. Down staging of the primary tumor is one of the important goals of neoadjuvant chemotherapy treatment (NCT), thereby permitting breast-conserving treatment without affecting the risk for a local relapse. Complete pathological response (pCR) rates after NCT vary across histological subtypes and can be more than 60% in HER2-positive disease with dual blockade therapy. Down staging of the axilla is also observed in patients initially presenting with metastatic lymph nodes. pCR rates in the axilla vary between 22% and 42% in reported series, again depending on tumor subtype. Omission of axillary lymph node dissection (ALND) can avoid the post-operative morbidity such as lymphedema in the short or long term follow-up.

Metastatic lymph node status is hard to be stated as a pCR in the axilla by using physical examination or imaging such as ultrasonography or tomography after complete NCT. Good response to the axilla lymph node causing the difficulty of tissue proof by using core needle biopsy, though the investigator knew that biopsy stands for the definite tool for the confirmation of the residual disease. One proposed method to decrease the false-negative rate (FNR) is clip placement in the positive node at initial diagnosis with confirmation of clipped node resection at surgery.

The correlation between the axillary lymph node identified on initial axillary ultrasound and the sentinel lymph nodes (SLNs) identified at surgery has not been fully evaluated. The concordance between percutaneous biopsy and the lymph node resected at the time of SLNB is not 100%. Sometimes, the initial node identified by ultrasound is not one of the SLNs. The impairment of the performance of SLNB might correlated to the alteration of lymphatic flow induced by tissue fibrosis or tumor deposits after NCT.

The investigator hypothesized that the clip placement at diagnosis of node-positive disease with removal of the clipped node during SLNB reduces the FNR of SLNB after NCT. Here, we evaluate how often the lymph node containing the clip placed at percutaneous biopsy before chemotherapy was found at surgery to be one of the SLNs, and how often it was found in the nodes retrieved at ALND. In addition, the investigator report the impact of identification of the clipped node within the SLNs on the FNR of SLNB.