Prognostic Nomograms to Predict Positive Lymph Nodes in Breast Cancer Patients after Neoadjuvant Chemotherapy: Competing Risk Models Basing on the SEER Database

Purpose: This study wanted to discuss whether sentinel lymph node biopsy (SLNB) combined with radiotherapy could be an alternative to axillary lymph node dissection (ALND) in patients with positive lymph nodes after neoadjuvant chemotherapy (NAC), and created nomograms to predict their probability of breast cancer-specific death (BCSD). Methods This study enrolled breast cancer patients who had positive lymph nodes after NAC, using data from the Surveillance, Epidemiology, and End Results (SEER) database. Patients were stratified into two groups based on whether they received radiotherapy. Stabilized inverse probability of treatment weighting was employed to correct confounding variables. Kaplan-Meier curves were utilized to compare breast cancer-specific survival (BCSS) and overall survival (OS) outcomes between SLNB and ALND. Furthermore, prognostic nomograms were developed to predict the probability of BCSD. Results A total of 2204 patients were enrolled in this study, including 1321 in the radiotherapy group and 883 in the non-radiotherapy group. In the radiotherapy group, there was no significant difference in BCSS ( HR  = 1.115, 95% CI 0.837–1.594, P  = 0.328) and OS ( HR  = 1.164, 95% CI 0.867–1.562, P  = 0.270) between SLNB and ALND subgroups. In the non-radiotherapy group, SLNB was associated with worse BCSS ( HR  = 1.912, 95% CI 1.273–2.873, P  < 0.001) and OS ( HR  = 1.754, 95% CI 1.219–2.523, P  = 0.001). The calibration curves and the areas under the curves demonstrated the excellent accuracy and consistency of the nomograms. Conclusions SLNB combined with radiotherapy in patients with positive lymph nodes after NAC may provide similar survival benefits as ALND. The nomograms may be able to predict the probability of BCSD for them.