Abstract P4-02-11: Can ultrasound replace sentinel lymph node biopsy in breast cancer staging of the axilla? Results from a single center retrospective review of axillary evaluation with conventional sonography and ultrasound elastography
Authors: Leong L , Upadhyaya V 
Published: March 2017

Abstract
Background and objective
Sentinel lymph node biopsy (SLNB) is the gold standard for axillary staging in clinically node negative breast cancer patients. Although generally safe and accurate, SLNB is an additional surgical procedure with occasional instances of false negatives and complications arising. Hence, there is interest in finding less invasive alternatives to SLNB. The aim of the study is to determine if ultrasound (US), together with adjunct US elastography (EI), has the potential to replace SLNB by evaluating its overall accuracy as well as the nodal disease burden in false negative cases.
Materials and methods
Axillary US evaluations in breast cancer patients performed in a single center institution over a 7 year period (2009-2015) were reviewed. Lymph nodes with histological assessments from percutaneous or surgical biopsies were included in the study. Cases which had histology obtained only after neoadjuvant chemotherapy were excluded. US assessment was based on the retrospective review of the attending radiologists' US reports. EI was based on the elastographic size ratio calculated from available elastographic images obtained before US percutaneous biopsy of lymph nodes. The sensitivity, specificity and false negative rates were correlated with histology as the gold standard. For false negative cases, the number of nodes involved and the size of the largest metastatic focus were recorded from available pathology reports.
Results
608 axillary US studies performed on 578 patients with invasive breast cancers were reviewed. 254 (41.8%) cases had nodal metastases and 354 (58.2%) had benign histology. Overall US sensitivity, specificity and false negative rates were 74.8%, 91.0% and 25.2% respectively.
Comparison of the ultrasound evaluation of lymph nodes against the final nodal status after histological evaluation Ultrasound impression MalignantBenignTotalNode statusMalignant190 (74.8%)64 (25.2%)254 Benign32 (9.0%)322 (91.0%)354 Total222386608
Of the 64 false negative cases, 81.3% (52/64) involved only 1 or 2 nodes, while false negative cases involving &gt; 2 nodes constituted 4.7% (12/254) of all nodal metastases. 32.1%, 19.6%, 26.8% and 21.4% of the false negatives had a nodal metastatic size of 0.2-2mm, &gt;2-5mm, &gt;5-10mm and &gt;10mm respectively (p=0.414). EI performed in 70 cases showed a sensitivity of 93.5% vs 97.8% (p=0.617) and specificity of 100% vs 58.3% (p&lt;0.001) when compared against conventional US.
Comparison of the diagnostic accuracy between conventional US and EI US impression EI impression malignantBenignMalignantBenignP-valueLymph node malignant (n=46)45 (97.8%)1 (2.2%)43 (93.5%)3 (6.5%)0.617Lymph node benign (n=24)10 (41.7%)14 (58.3%)0 (0%)24 (100%)&lt;0.001
Conclusion
US is fairly accurate in the evaluation of axillary nodal disease. Even in false negative cases, the nodal disease burden is low, potentially not affecting prognosis. Hence, axillary US staging has the potential to replace SLNB. Adding EI to conventional US evaluation will not significantly reduce the false negative rate but may help reduce unnecessary biopsies.
Citation Format: Leong L, Upadhyaya V. Can ultrasound replace sentinel lymph node biopsy in breast cancer staging of the axilla? Results from a single center retrospective review of axillary evaluation with conventional sonography and ultrasound elastography [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-02-11.