Abstract P4-02-11: Can preoperative axillary staging replace sentinel node biopsy? Comparison of preoperative axillary and final histologic nodal findings in 2108 patients with primary breast cancer

Background Axillary staging is an integral part of the preoperative work-up in patients with breast cancer. Given the increasing number of patients treated with neoadjuvant chemotherapy (NC) and current guidelines to perform sentinel-node biopsy after the completion of neoadjuvant chemotherapy, axillary staging has gained more importance. Beside the prediction of nodal involvement, correct prediction of nodal stage is crucial in order to select respective treatment for the patients. Materials and Methods Patients treated for primary breast cancer from 01/2013 to 01/2018 and received preoperative sonografic axillary staging and surgery were identified from the breast databases of two large volume hospitals. In case of sonografic suspicion of nodal involvement an axillary biopsy was performed. Accuracy of axillary staging was examined regarding the concordance between prediction of nodal involvement and nodal (N) stage with final pathology. A multivariate model was used to identify factors associated with a high accuracy of axillary sonografic staging. Results Among 2220 patients, 112 were excluded due to incomplete clinical data or axillary surgery after completion of neoadjuvant chemotherapy leaving 2108 patients for final analysis. 1535 (73 %) showed a N0 stage on final pathology. Accuracy of axillary staging regarding prediction of nodal involvement was 92 % (1929/2108) with a sensitivity of 80 % and a specificity of 96 %, a positive predictive value of 88 % and a negative predictive of 93 %. Prediction of nodal stage was correct in 1894 of 2018 cases (90 %). Concordance between sonografic prediction of N stage and final pathology decreased with higher nodal stages (N0 - 91 %, N1 84 %, N2 81 %, N3 68 %) and was higher in node negative patients (91 %) compared to node positive patients (86 %; p ≤ 0.05). On multivariate analysis the presence of nodal involvement was the only factor associated with concordance of axillary staging and pathologic nodal stage (OR 0.11 (95 %CI 0.08 - 0.16) p ≤ 0.01). Conclusion In this large population of patients with primary breast cancer, we showed a high accuracy of preoperative axillary staging with respect to nodal involvement and prediction of respective N stage. With a negative predictive value of 93 % regarding node negativity, axillary staging showed accurate outcomes but improvements in sensitivity are necessary in oder to compete with sentinel node biopsy. Citation Format: Julia Caroline Radosa, Martin Deeken, Lisa Stotz, Sarah Huwer, Carolin Muller, Rosemarie Weinmann, Christoph G Radosa, Marc P Radosa, Stefan Wagenpfeil, Erich-Franz Solomayer. Can preoperative axillary staging replace sentinel node biopsy? Comparison of preoperative axillary and final histologic nodal findings in 2108 patients with primary breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-02-11.