Abstract PS1-31: Nomogram for predicting axillary lymph node pathological response in node-positive breast cancer patients after neoadjuvant chemotherapy

Abstract

Abstract Background: Pathological complete response (pCR) of axillary lymph nodes (ALNs) is frequently achieved in patients with clinically node-positive breast cancer after neoadjuvant chemotherapy (NAC). ALN status is an important prognostic factor for choosing the type of axillary lymph node surgery. Many patients with axillary pCR could replace axillary lymph node dissection (ALND) with sentinel lymph node biopsy (SLNB). Our goal is to develop a new predictive clinical model to detect axillary pCR after NAC and provide clinical clues for avoiding ALND. Methods: A retrospective series of 547 patients who had biopsy-proven positive ALNs at diagnosis from 2007 to 2014 in National Cancer Center/Cancer Hospital of Chinese Academy of Medical Sciences were involved. We analyzed the clinicopathologic features and developed a nomogram to predict the probability of ALN pCR. Univariate assessment was performed using chi-square test. A multivariate logistic regression stepwise model was used to generate a nomogram to predict ALN pCR in node positive patients. The receiver operating characteristic (ROC) curve was established and the area under the curve (AUC) was calculated to evaluate the accuracy of the model. Internal validation was estimated using 50-50 hold out validation method. Nomogram was validated externally with the prospective cohorts of 167 patients from 2016 to 2018 of Cancer Hospital of Chinese Academy of Medical Sciences and 75 patients from 2018 to 2019 of Beijing Tiantan hospital.Results: In the retrospective study, 172 (31.4%) patients achieved axillary pCR after NAC. Multivariate analysis indicated that clinical nodal (N) stage, hormone receptor (HR) status and clinical response of primary tumor after NAC were significant independent predictors for axillary pCR (P<0.05). The AUCs of the internal validation for the training and test sets were 0.719 and 0.753, respectively. The nomogram was validated in external cohorts with AUCs of 0.862 and 0.766, respectively.Conclusion: We developed a nomogram to predict axillary pCR in node positive breast cancer patients after NAC. The predictive model performed well in prospective external validation. This practical tool could provide information to surgeons about whether to avoid ALND after NAC. Citation Format: Xin Wang, Wenyan Wang, Jiaxiang Liu, Xiangzhi Meng, Jiaqi Liu, Changyuan Guo, Ying Song, Ningyi Cui, Qiao Li, Zeyu Xing, Jie Wang, Menglu Zhang, Kexin Feng, Pilin Wang, Xiang Wang. Nomogram for predicting axillary lymph node pathological response in node-positive breast cancer patients after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-31.