Abstract PO3-03-03: Prospective non-randomized study to compare accuracy of clinical examination under anesthesia, axillary ultrasound and histo-pathological evaluation for axillary nodal staging in women with clinically N0 early breast cancer

Abstract Introduction: Accurate assessment of axillary lymph nodes is crucial in the management of early breast cancer (EBC), especially in clinically node negative (cN0) axilla to avoid extensive axillary surgery. Clinical examination alone underestimates nodal disease in nearly 30% women with cN0 axilla. The current study compares, in cN0 axilla, the benefit of axillary ultrasonography (USG) and clinical axillary examination under anesthesia (EUA) to predict involvement of axillary lymph nodes. The gold standard in these patients however remains pathological evaluation after sentinel node biopsy/low axillary sampling (SNB/LAS) and a complete axillary lymph node dissection (ALND) if node positive. Methodology: Prospectively, 500 women with cN0 EBC were enrolled from Aug 2015 to April 2023 in a study approved by Institutional Ethics Committee. After informed consenting, a preoperative axillary USG was carried out in addition to standard breast imaging to determine number of axillary node(s) and its architecture. The USG assessment was labeled as suspicious or not and the result was blinded to the surgeons. A USG-guided FNAC was not performed as it would then be difficult to blind the surgeon and pathologist preoperatively. During surgery, an initial axillary EUA was performed before starting and any suspicious node was documented. This was followed by axillary staging by standard dual tracer SNB/LAS. A complete axillary dissection was done (level 1-3) if any node was positive on frozen section evaluation or final histopathology. Axillary node histopathology was the gold standard for comparison of effectiveness of clinical exam, USG, EUA, and SNB/LAS for prediction of axilla. Standard diagnostic tests such as sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were used. Results: Thirty-six patients were excluded in the final analysis (disease progression, chemotherapy first, or had a surgery elsewhere). Of the eligible 464 cN0 patients, 129 were detected to have axillary metastases (27.8%) in final histopathology. The 2 interventions namely USG axilla, EUA were compared to final axillary nodal histopathology. Axillary USG reported suspicious/indeterminate node(s) in 129 (27.8%) patients. USG had a low sensitivity of 46.5% and a low PPV of 46.5% to identify a positive node. However, the specificity and NPV both were 79.4%. Axillary USG was 70.2% accurate in predicting axillary nodal involvement. EUA also had sensitivity of 60% and low PPV of 14.8%. However, the specificity of EUA was 73.4%, NPV of 95.9%; higher than that of USG. EUA was 72.4% accurate. SNB/LAS had the sensitivity of 93.3%, specificity 79.2%, NPV 82.9%, PPV 91.6% and accuracy rate 89.2% in predicting a positive axilla. Conclusions: While the fallacy of clinical exam remains at 27.8%, both USG alone (without FNAC) and EUA failed in predicting a positive axillary node. EUA fared better at predicting a negative axilla. USG guided FNAC would perhaps improve the sensitivity of USG, however additional investigations are difficult in resource constraint and high-volume center, especially, when surgical interventions like SNB or LAS remain standard of care. Table 1 Citation Format: Vani Parmar, Zeal Sanghvi, Shalaka Joshi, Nita Nair, Palak Popat, Seema Kembhavi, Souwmyashree KN, Soujanya Mynalli, Purvi Thakkar, Garvit Chitkara, Sangeeta Desai, Tanuja Shet, Rajendra Badwe. Prospective non-randomized study to compare accuracy of clinical examination under anesthesia, axillary ultrasound and histo-pathological evaluation for axillary nodal staging in women with clinically N0 early breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-03-03.