Abstract PS1-51: A nomogram for predicting three or more axillary lymph node involvement before breast cancer surgery

Abstract

Abstract Introduction Focus has moved to de-escalate of axillary surgery in the management of early breast cancer. Based on the American College of Surgeons Oncology Group-Z0011, our team created the nomogram to be useful for identifying patients who do not require intraoperative analysis of the sentinel lymph node. The nomogram could identify as patients likely to three or more positive axillary lymph nodes by preoperative imaging. But the nomogram had several limitations. This study investigated a developed nomogram by excluding the chest computed tomography (CT) and adding 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT as a modality. Material and Methods Patients underwent preoperative ultrasonography (US) and PET/CT. The training set consisted of 1030 patients with clinical T1-2 and node-negative invasive breast cancer. Factors associated with ≥ 3 involved axillary lymph nodes (ALNs) were evaluated by logistic regression analysis. The validation set consisted of 781 independent patients. The nomogram was applied to 1,067 patients who met the selection criteria of the ACOSOG-Z0011. Results Of the 1,030 patients, 89 (8.6%) had ≥ 3 positive nodes. Multivariate analysis according to be used for making a new nomogram to predict the probability of involvement ≥ 3 nodes, there was significantly associated with larger tumor size, higher grade ultrasonographic ALN classification, and findings suspicious of positive ALN on PET/CT. The areas under the receiver operating characteristic curve of the nomogram were 0.856 (95% confidence interval [CI], 0.815 to 0.897) for the training set and 0.866 (95% CI, 0.799 to 0.934) for the validation set. Application of the nomogram to the patients who met the ACOSOG-Z0011 showed that 90/1067 (8.4%) had scores above the cut-off and the false-negative rate was 37/977 (3.8%). And the specificity was 93.8%, and the negative predictive value was 96.4%. Conclusion The upgraded nomogram improved predictive accuracy, and that was possible using only US and PET/CT. It reduced operation time and cost, with a very low re-operation rate. This nomogram is useful for identifying patients who do not require intraoperative analysis of sentinel lymph nodes. Citation Format: Young-Joon Kang. A nomogram for predicting three or more axillary lymph node involvement before breast cancer surgery [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 PS1-51.