Development and Validation of a Preoperative Scoring System to Distinguish Between Nonadvanced and Advanced Axillary Lymph Node Metastasis in Patients With Early-stage Breast Cancer.

BACKGROUND

It has been determined that axillary lymph node dissection after the detection of limited axillary lymph node metastasis does not improve the prognosis of patients with breast cancer. Thus, a need exists for less-invasive axillary surgery. However, it remains unclear whether a predictive model based on preoperative data would be sufficient to accurately predict the probability of pN2-N3 (> 3 lymph node metastases). We sought to develop an easy-to-use scoring system to distinguish between pN0-N1 (0-3 lymph node metastases) and pN2-N3 using only preoperative data and validate its predictive performance.

PATIENTS AND METHODS

We retrospectively identified 2687 patients diagnosed with cT1-3cN0-N1 who had undergone surgery in our hospital from 2013 to 2019. We evaluated the risk factors associated with pN2-N3 by logistic regression analysis and developed a scoring system. Predictive performance was assessed by calculating the receiver operating characteristic area under the curve (AUC) and was validated using K-fold cross-validation.

RESULTS

We identified 1987 patients with stage pN0, 522 with pN1, and 178 with pN2-N3. Multivariate analysis revealed tumor size, number of suspicious lymph nodes on axillary ultrasound examination, histologic type, histologic grade, and receptor status were significant risk factors for pN2-N3. The AUC value was 0.87, and the mean AUC of the 10-fold cross-validation was 0.88. When the cutoff score was set at 6, the negative predictive value for excluding patients with pN2-N3 was 98.4%.

CONCLUSION

Our easy-to-use scoring system could be useful to preoperatively identify patients at lower risk of pN2-N3 and avoid unnecessary axillary lymph node dissection.