Abstract P3-01-14: Nomogram predicting axillary lymph node metastases to skip intraoperative analysis of sentinel lymph nodes

Abstract

Background: According to the American College of Surgeons Oncology Group Z0011 trial, complete axillary lymph node dissection (ALND) did not affect survival of patients with clinical T1-T2 invasive breast cancer and one to two sentinel lymph nodes (SLNs) metastases treated with lumpectomy, adjuvant systemic therapy, and radiation therapy. A significant proportion of breast cancer patients may not require ALND, in whom intraoperative analysis of SLNs can be omitted reducing operation time and cost. The aim of this study was to develop a nomogram predicting three or more axillary lymph nodes (ALNs) metastases based on preoperative imaging and clinicopathological factors. Methods: The training set consisted of 1030 patients with clinical T1-T2 invasive breast cancer and clinically negative ALN who received surgery at Seoul National University Hospital (SNUH) between January 2010 and December 2013. Preoperative imaging techniques including ultrasonography (US), computed tomography (CT), positron emission tomography (PET), and clinicopathological features associated with three or more ALN metastases were evaluated by logistic regression analysis. A nomogram predicting three or more ALNs was developed with statistically significant factors. The validation set consisted of 781 independent patients who received surgery at SNUH between January 2014 and December 2015. Results: Of the 1030 patients, 89 (8.6%) had three or more ALN metastases. Multivariate analysis showed that three or more ALN metastases was independently associated with tumor size (cm) by US (p<0.001), suspicious ALNs findings in US (p<0.001), chest CT (p<0.001), and PET/CT (≥ 1.4 SUV, p<0.001). Established nomogram evaluating the probability of three or more ALNs metastases includes the above four associated factors. The areas under the receiver operating characteristic (ROC) curve of the nomogram were 0.866 (95% confidence interval [CI] 0.826-0.905) for the training set and 0.867 (95% CI: 0.801-0.932) for the validation set. With cutoff point of 142, false negative ratio is 3.6%, and 8.6% of patients were candidates for intraoperative SLN analysis. Conclusion: Patients with a strong possibility of three or more ALNs metastases can be identified using preoperative imaging methods including US, CT, and PET. The nomogram measuring this prospect may be valuable in skipping intraoperative analysis of SLNs with advantage of reduced operation time and cost. Citation Format: Park JH, Ju YW, Kim KE, Rhu J, Kim Y, Lee E, Lee H-B, Moon H-G, Noh D-Y, Han W. Nomogram predicting axillary lymph node metastases to skip intraoperative analysis of sentinel lymph nodes [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-01-14.