Objective To investigate the prognosis of patients with negative sentinel lymph nodes (SLN) after neoadjuvant chemotherapy (NAC) for breast cancer who are exempt from axillary lymph node dissection (ALND) and evaluate its safety in clinical treatment.

Methods Clinical data of 2, 163 patients initially diagnosed with breast cancer and having negative SLNs after NAC were selected from the SEER database from 2018 to 2021. Among them, 373 patients underwent only SLN biopsy (SLNB group), and 1, 790 patients underwent ALND (ALND group). Propensity score matching (PSM) was used to control for confounding factors, and the Kaplan-Meier method was employed to analyze the overall survival rate. Univariate and multivariate Cox regression analyses were conducted to identify prognostic factors influencing the exemption from ALND in patients with negative SLNs after NAC for breast cancer.

Results Before PSM, significant differences were observed between the two groups in terms of clinical tumor stage, molecular subtype, estrogen receptor (ER) status, progesterone receptor (PR) status, human epidermal growth factor receptor 2 (HER-2) status, efficacy of NAC, and breast surgery method (P < 0.05). After PSM, 363 patients were included in each group. Univariate Cox regression analysis after PSM revealed that age, clinical tumor stage, and ER status were associated with overall survival (OS) of patients (P < 0.05). There was no significant difference in OS between patients who underwent SLNB and those who underwent ALND (P>0.05). Multivariate Cox regression analysis indicated that age and clinical tumor stage were independent factors influencing OS in patients with negative SLNs after NAC. Survival curve analysis after PSM showed no statistically significant difference in overall survival rate between the SLNB and ALND groups (P=0.278).

Conclusion Exemption from ALND in patients with negative SLNs after NAC is feasible and does not affect the overall survival rate of patients.