Predictive factors for nonsentinel lymph node metastasis in patients with positive sentinel lymph nodes after neoadjuvant chemotherapy: Nomogram for predicting nonsentinel lymph node metastasis

Abstract Introduction Axillary lymph node (ALN) status is an important prognostic factor for breast cancer patients. With increasing numbers of patients undergoing neoadjuvant chemotherapy (NAC), issues concerning sentinel lymph node biopsy (SLNB) after NAC have emerged. Patients and Methods We analyzed clinicopathological features and developed a nomogram to predict the possibility of nonsentinel lymph node (NSLN) metastases in patients with positive SLNs after NAC. A retrospective chart review was performed for 140 patients who were clinically ALN positive at presentation, had a positive SLN after NAC on subsequent SLNB, and underwent axillary lymph node dissection (ALND) between 2008 and 2014. Results On multivariate stepwise logistic regression analysis, pathologic T stage, LVI, SLN metastasis size, and number of positive SLN metastases were independent predictors for NSLN metastases (P < .05). The NAC nomogram was based on these four variables. A receiver operating characteristic curve was plotted and the area under the curve (AUC) was 0.791 for the NAC nomogram. In internal validation of performance, the AUCs were 0.801 and 0.760. The nomogram was validated in an external patient cohort with an AUC of 0.705. Conclusion The Samsung Medical Center (SMC) NAC nomogram was developed to predict the likelihood of additional positive NSLNs. The SMC NAC nomogram could provide information to surgeons regarding whether to decide additional ALND when the permanent biopsy revealed positive even though intraoperative SLNB was negative.