Abstract P2-18-04: No further axillary dissection in sentinel lymph node-negative breast cancer after neoadjuvant chemotherapy in patients with initial cytologically-proven axillary node metastasis

Background In patients with fine needle aspiration (FNA)-proven axillary lymph node metastasis at diagnosis (cN+), the current standard surgical procedure is axillary lymph node dissection (ALND) at definitive surgery after neoadjuvant chemotherapy (NAC). However, growing evidences suggest that SLNB after NAC is feasible and may demonstrate acceptable performance in selected patients. We performed sentinel lymph node biopsy in patients treated with cytologically-confirmed axillary lymph nodes metastases at presentation, who converted to a clinically negative axillary status after NAC (ycN0). Patients and methods We retrospectively evaluated 240 patients with invasive breast cancer with ultrasound-guided FNA-proven axillary nodal metastases at the time of diagnosis. All patients received NAC and underwent surgery at Samsung medical center between October 2007 and May 2013. Among these patients, 75 patients underwent SLNB. These patients converted to clinically node-negative disease (ycN0) after NAC on breast MRI or PET/CT scan. A combined detection technique was used with radioisotope and blue dye for the detection of SLN. Patients with negative SLN on frozen pathology and low clinical suspicion of metastasis during operation were not performed further ALND. Results The detection rate of SLNB was 93.3% (70/75), and median number of retrieved sentinel lymph nodes was 3.0 (range 1-8). False negative rate was 6.7% (1/15). Of these 75 patients, 35 (46.6%) patients had positive sentinel lymph nodes (ypN+) and underwent ALND. Thirty-five (46.6%) patients had tumor-free sentinel lymph nodes (ypN0sn) and 20 patients of them were followed without subsequent ALND. In these SLN-negative patients without further ALND, 9 patients were HER2-enriched subtypes and 9 patients, TNBC subtypes. Only two of them were Luminal B subtypes. The median follow-up period was 12.0 months (range 0-26 months) with 2 events; 1 regional recurrence in ipsilateral supraclavicular node and 1 systemic recurrence in brain on postoperative 7 months and 5 months, respectively. There has not occurred an ipsilateral axillary recurrence so far. Conclusions Although the follow-up was not long enough to conclude, this study tried to demonstrate that SLNB after NAC was feasible and further ALND may not be necessary in patients with SLN-negative disease (ypN0sn). Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-18-04.