Axillary lymph node status is one of the most important prognostic factors in primary breast carcinomas. Sentinel lymph node biopsy has been increasing in post neoadjuvant setting when axillary nodes show good clinical and radiological response. It allows to determine the axillary lymph node status, which if negative, saves the patient from axillary dissection (AD) and its potential complications. To assess tumor response to neoadjuvant chemotherapy in the SLN, pathological evaluation is the gold standard. Response to neoadjuvant systemic therapy is an excellent predictor of outcome, and achievement of pathological complete response (PCR) in the SLN is a prognostic predictor of long-term outcome with significantly better disease-free survival and overall survival. Post-treatment isolated tumor cells (ITCs) and micro metastases predict worse survival compared with the same findings in the non-neoadjuvant setting. Histologically partial response to therapy, is characterized by small clusters and individual tumor cells set in hyaline stromal fibrosis. Most false negative cases had metastatic foci identified exclusively on permanent sections and are not due to a true diagnostic interpretation error. The timing of further axillary surgery, immediate or a subsequent operation should be routinely discussed at centers using intraoperative assessment of the sentinel lymph nodes, along with the potential for negative intraoperative findings and positive nodes on final pathology.

Inclusion Criteria:

1. Patients greater than 18 years of age
2. All diagnosed breast carcinoma patients ranging from T1 to T4 and N0 to N1, who have received neoadjuvant chemotherapy will be included.

Exclusion Criteria:

1. Poorly preserved biopsy material, insufficient to assess all the histological features.

All patients who were initially diagnosed with breast cancer greater than 18 years, stage T1 to T4, N0 to N1 by Section of Histopathology, Aga Khan University Hospital, Karachi from 2021 to 2022 and subsequently received neoadjuvant chemotherapy, were included.

Demographic details including age, diagnosis and results including sensitivity, specificity, and false negative rate of frozen SLNB after neoadjuvant chemotherapy.