Abstract P3-01-10: Sentinel lymph node biopsy after neoadjuvant chemotherapy for patients with clinically node-positive breast cancer: A single institution retrospective evaluation

Abstract

Abstract Background: In patients with clinically node-negative breast cancer sentinel lymph node biopsy (SLNB) offers accurate staging information with considerably less morbidity than a full axillary lymph node dissection (ALND). However, for clinically node-positive (cN1) patients who undergo neoadjuvant chemotherapy SLNB is thought to have a high false-negative rate and not suitable for this population. We sought to evaluate the false-negative rate (FNR) of SLNB following chemotherapy in patients initially presenting with cN1 breast cancer at a single institution. Methods: Patients undergoing neoadjuvant chemotherapy diagnosed with cN1 breast cancer between October 2004 and February 2014 were identified from the University of California, San Francisco cancer registry. All patients underwent single agent mapping with Tc99 and SLNB followed by completion axillary lymph node dissection (ALND). Pathologic complete response, number of sentinel nodes removed and FNR were calculated. Results: Of the 80 patients who underwent SLNB and ALND, 43 had residual metastatic disease in the nodes producing a nodal pCR of 46.25% (95%CI. 35.0%-57.8%). In 14 patients, cancer was not identified in the SLNs but was discovered in the lymph nodes retrieved by ALND, resulting in an overall FNR of 32.6% (95% CI, 19.1%-48.5%). 49 patients had only 1 SLN removed. Of the patients with only 1 SLN removed, a false-negative SLN was identified in 9 of the 21 patients with a positive node for a FNR of 42.9% (95% CI, 21.8%-66.0%). Of the patient with more than 1 SLN removed, 5 of 18 patients with a positive node had a false-negative SLN yielding a FNR of 27.8% (95% CI, 9.7%-53.5%). Only 14 patients had more than two SLNs excised. Conclusion: Recent studies including the French GANEA 2 and ACOSOG Z1071 trials demonstrated a significant decrease in FNR when more than 1 SLN was excised. In this retrospective study however a single SLN was sampled from most patients. The FNR from this study was more than three times the generally accepted threshold of 10%. This substantial FNR further supports the need to remove more than 1 SLN during surgery in order to accurately assess nodal disease. Furthermore the implementation of a dual mapping technique would likely facilitate this process. Citation Format: Gallant E, Ewing C, Wong J, Esserman L, Alvarado M. Sentinel lymph node biopsy after neoadjuvant chemotherapy for patients with clinically node-positive breast cancer: A single institution retrospective evaluation. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-01-10.