PUMCH-SLN nomogram for the preoperative prediction of sentinel lymph node metastasis in breast cancer

Abstract Background: To investigate associations between clinicopathological features and sentinel lymph node (SLN) status of breast cancer, then constructed a nomogram to predict SLN metastasis.Methods: Patients treated with SLN dissection from 2014 to 2019 at Peking Union Medical College and Hospital (PUMCH), were retrospectively analyzed as the training set (n = 472). Lymph node ultrasound and pathological characteristics were compared using chi-squared and t-tests. To verify the accuracy of the model, internal (n = 175) and external (3 centers, n = 81) validation groups were established for patients in 2019. A nomogram predicting SLN metastasis was constructed using multivariable logistic regression models; discrimination and calibration of the nomogram were assessed by C statistics and calibration curve. Clinical use by decision curve analysis.Results: In the training set the SLN+ rate was 23.73%. Statistically significant factors associated with SLN positivity were: histology type (P < 0.001); PR (P = 0.003); Her-2 status (P = 0.049); and ultrasound lymph node (ALN-US) shape (P = 0.034), corticomedullary demarcation (P < 0.001), and blood flow (P = 0.001). Five independent variables were integrated into the nomogram (C-statistic 0.714 [95% CI: 0.688-0.740], validated internally (0.816 [(95% CI: 0.784-0.849]) and externally (0.942 [95% CI: 0.918-0.966]). Thus, the model had good predictive accuracy and clinical applicability.Conclusions: The PUMCH-SLN nomogram provides a direct and reliable tool for prediction and individual evaluation of SLN status preoperatively, emphasizing the role of ALN-ultrasound morphology for predicting SLN metastasis. This nomogram should aid decisions concerning ALN dissection and adjuvant treatment.