A Multicenter Retrospective Analysis on Lymph Node Metastasis in Clinically Node-Negative (cN0) Patients with Small-Sized Breast Cancer

Xueqin Yan,1,* Yinjiao Fei,1,* Tianfu Dong,1,2,* Zhen Zhu,1 Zhaohui Zhu,3 Wen Gao,1 Dandan Wang,1 Jian Zhang1 1Department of Thyroid and Breast Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China; 2Lianyungang Clinical College of Nanjing Medical University, The First People’s Hospital of Lianyungang City, Lianyungang, Jiangsu, People’s Republic of China; 3Department of Thyroid and Breast Surgery, The Affiliated Huai’an Hospital of Xuzhou Medical University, Huai’an, Jiangsu, People’s Republic of China*These authors contributed equally to this workCorrespondence: Dandan Wang, Email [email protected] Jian Zhang, Email [email protected]: Sentinel lymph node biopsy (SLNB) is the standard for early breast cancer, but its necessity in small tumors with clinically node-negative (cN0) status remains debated. This study evaluated the incidence of lymph node metastasis in cN0 patients to explore the feasibility of omitting axillary surgery.Methods: A cohort of 579 women with unilateral small breast cancer and cN0 were enrolled from three hospitals in Jiangsu Province (March 2023–June 2024). Clinical nodal status was determined by ultrasonography, while pathology and immunohistochemistry assessed tumor size, node status, and molecular subtypes. Chi-square tests and logistic regression were used for analysis.Results: Lymph node metastasis was detected in 79 patients (13.64%). Tumors ≤ 20 mm and Ki-67 ≤ 14% showed significantly lower metastasis rates (P < 0.0001 and P = 0.013, respectively). Even in cN0 patients with both favorable factors, 6.15% still had nodal involvement. Logistic regression identified tumor size (T2) as an independent predictor of metastasis.Conclusion: Small breast cancer with cN0 and low Ki-67 expression is associated with reduced but non-negligible nodal metastasis. These findings support caution in omitting axillary surgery and highlight the need for individualized risk stratification rather than universal omission.Keywords: breast cancer, axillary surgery, lymph node metastasis, molecular subtypes