Are Breast Cancer Nomograms Still Valid to Predict the Need for Axillary Dissection?

ABSTRACT

BACKGROUND: Nomograms can help in estimating the nodal status among clinically node-negative patients. Yet their validity in external cohorts over time is unknown. If the nodal stage can be estimated preoperatively, the need for axillary dissection can be decided. OBJECTIVES: The aim of this study was to validate three existing nomograms predicting 4 or more axillary lymph node metastases. METHOD: The risk for ≥4 lymph node metastases was calculated for n = 529 eligible breast cancer patients using the nomograms of Chagpar et al. [Ann Surg Oncol. 2007;14670-7], Katz et al. [J Clin Oncol. 2008;26(13)2093-8], and Meretoja et al. [Breast Cancer Res Treat. 2013;138(3)817-27]. Discrimination and calibration were calculated for each nomogram to determine their validity. RESULTS: In this cohort, the AUC values for the Chagpar, Katz, and Meretoja models were 0.79 (95% CI 0.74-0.83), 0.87 (95% CI 0.83-0.91), and 0.82 (95% CI 0.76-0.86), respectively, showing good discrimination between patients with and without high nodal burdens. CONCLUSION: This study presents support for the use of older breast cancer nomograms and confirms their current validity in an external population.