Non-Sentinel Node Metastasis Prediction During Surgery in Patients with Breast Cancer with One to Three Positive Sentinel Node(s) Upon Frozen Biopsy Result Following Neoadjuvant Chemotherapy

We aimed to develop a tool that could accurately predict the possibility of non-sentinel lymph node metastasis (NSLNM) during surgery, permitting surgeons to intraoperatively decide the extent of further axillary lymph node dissection (ALND) for patients with one to three positive sentinel lymph node(s) (SLN) following neoadjuvant chemotherapy (NAC). In this retrospective analysis, we included records of 558 patients who were treated between 2005 and 2019. Using chi-square and logistic regression with a bootstrapped, backward elimination method, 13 factors were assessed for their utility in predicting NSLNM. Based on the results of the univariate analysis, the number of positive SLN(s), number of frozen nodes, progesterone receptor (PR) positivity, and clinical N stage were selected for the multivariate analysis and used to generate a nomogram for residual nodal disease prediction. The resulting nomogram was validated using a more recent, different time window patient group at the AMC. The area under the receiver operating characteristic curve of this formula was 0.709 (95% confidence interval [CI], 0.658–0.761) and 0.715 (95% CI, 0.634–0.796) for the development and validation sets, respectively. This newly developed AMC nomogram could be useful for surgeons for intraoperative guidance in determining the extent of further axillary surgery.