Predicting the risk of non-sentinel lymph node metastasis in breast cancer patients with 1-2 positive sentinel lymph nodes

Objective To evaluate the risk factors of non-sentinel lymph node (NSLN) metastasis in breast cancer patients with 1-2 positive sentinel lymph nodes and to establish a new Nomogram prediction model. Methods Clinicopathological data of breast cancer patients who were diagnosed with 1–2 positive lymph nodes and underwent axillary lymph node dissection (ALND) without neoadjuvant chemotherapy from January 2008 to December 2014 were retrospectively analyzed. Measurement data between two groups were analyzed by chi-square test. Multivariate analysis was performed by logistic regression model. The prediction accuracy of the Nomogram model was evaluated using the area under the receiver operating characteristic curve (AUC) and calibration curves. Results A total of 270 patients were recruited in this study. Among them, 87(32.2%) patients had NSLN metastases. The median age was 46 years old (21-80 years), the median number of SLNs was 4(1-10) and the median number of axillary lymph nodes was 20(10-41). Univariate analysis demonstrated that the pathological grade, the size of SLN metastasis, the number of negative and positive SLNs were the risk factors of NSLN metastasis (P=0.001-0.045). Multivariate analysis showed that pathological grade, the number of negative and positive SLNs were independent risk factors of NSLN metastasis (P=0.000-0.041). The AUC value of Nomogram prediction model for NSLN metastasis was 0.70.The false negative rate of Nomogram was 10.5% when the cut-off point of predictive probability was ≤ 15%. Conclusions The Nomogram is a useful prediction model for evaluating NSLN metastasis. ALND or axillary radiotherapy can be avoided for patients with a low probability of NSLN metastasis. Key words: Breast neoplasms; Sentinel lymph node; Non-sentinel lymph node; Prediction model