Risk Factors for Non-sentinel Lymph Node Metastasis in HR+/HER2- Breast Cancer With cN0.

Background/aim: This study aimed to identify the risk factors associated with non-sentinel lymph node (non-SLN) metastasis in case of hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer with cN0 on preoperative exam, where the sentinel lymph node (SLN) is positive.

Patients and methods: We conducted a retrospective review of medical records from the Chonnam National University Hwasun Hospital, spanning from January 2013 to January 2020, focusing on patients with HR+, HER2- breast cancer. Specifically, we collected the clinical and pathological data for those patients who underwent axillary lymph node dissection (ALND) due to positive SLN.

Results: Among the 166 patients who underwent ALND after positive SLNs, median patient age was 52 years. Univariate analyses demonstrated a significant association between non-SLN metastasis and the number of positive SLNs (p=0.039), SLN positive ratio (p<0.001), and primary tumor size (p=0.018). Multivariate analysis revealed that an SLN ratio >0.55 (p=0.004, HR=3.007, 95% CI=1.427-6.335) was independently associated with non-SLN metastasis. However, neither the number of positive SLN nor primary tumor size showed associations with non-SLN metastases.

Conclusion: In patients with HR+, HER2- breast cancer who are cN0, completion of ALND should be considered when the positive SLN ratio is ≥0.55. This approach aims to provide the opportunity for survival benefit through additional adjuvant therapy or to contribute to de-escalation of unnecessary surgery.