71P - Is sentinel lymph node biopsy necessary in breast cancer patients who were diagnosed as initially clinically node-negative before neoadjuvant chemotherapy?

Abstract

Background: Neoadjuvant chemotherapy (NAC) is established for treatment of locally advanced disease and is being used increasingly for early-stage breast cancer. And sentinel lymph node biopsy (SLNB) for clinically node-negative (cN0) breast cancer patients after NAC is performed as a daily procedure. The purpose of this study was to identify the group that can omit SLNB in patients with cN0 breast cancer at diagnosis before NAC. Methods: A retrospective analysis was performed of 69 patients who were diagnosed as cN0 before NAC and underwent SLNB between 2005 and 2016. Before NAC, all patients underwent clinical assessment of lymph node status by ultrasound. We judged patients to be node-negative when ultrasound showed no suspicious nodes, and if axillar lymph nodes were swelling, fine needle aspiration cytology was performed. 62 patients received anthracycline-based chemotherapy and 6 patients received taxane alone. SLNB procedure and partial resection was done after NAC in all patients. Lymphatic mapping was performed with radioactive colloid and lymphatic blue dye. Results: Median follow-up time was 48 months. Success rate for the identification and removal of SLNs was 94.2% (65/69). The median number of SLNs removed was 2. In breast cancer patients who were diagnosed as cN0 before NAC, only 5 patients (7.2%) represented SLN involvement and were performed axillar dissection. And the SLNs were the only positive nodes in 3 patients. No SLN metastases were observed in 11 patients who were diagnosed as clinical complete response (cCR) by ultrasound and MRI. But 5 patients (9.3%) had positive SLN in the 54 patients who were diagnosed as clinical partial response or clinical stable disease (p = 0.38). Tumor size, hormone receptor status and HER2 status did not influence the positive rate of SLN metastases. No axillar lymph node recurrence was observed within follow-up period. Conclusions: Our results show that SLNB is necessary even in breast cancer patients who were diagnosed as cN0 before NAC. But SLNB may be omitted in breast cancer patients who were diagnosed as cN0 before NAC and as cCR by ultrasound and MRI after NAC. Legal entity responsible for the study: Jichi Medical University Funding: None Disclosure: All authors have declared no conflicts of interest.