Real-world Outcomes of Postoperative Management for Sentinel Lymph Node-positive Breast Cancer Without Intraoperative Assessment: A Single-institution Retrospective Study.

[BACKGROUND/AIM] Sentinel lymph node biopsy (SLNB) has become the standard procedure for axillary staging in clinically node-negative breast cancer. Traditionally, axillary lymph node dissection (ALND) has been performed when intraoperative pathological assessment revealed sentinel lymph node (SLN) metastasis. However, growing evidence suggests that postoperative radiotherapy and systemic therapy may safely replace ALND in selected patients, challenging the clinical necessity of intraoperative SLNB assessment.

[PATIENTS AND METHODS] We retrospectively reviewed 540 patients with stage I-III primary breast cancer who underwent curative surgery and SLNB without intraoperative pathological evaluation between January 2018 and December 2021. Clinicopathological characteristics, adjuvant treatment strategies, and survival outcomes were analyzed, with a focus on patients with SLN metastases.

[RESULTS] SLN metastases were identified in 87 patients. Postoperative management consisted of ALND (n=19), axillary radiotherapy (n=39), systemic therapy alone (n=28), or no further treatment (n=1). Patients undergoing ALND showed a significantly higher recurrence rate compared with other treatment groups (=0.028, log-rank), though ALND was more commonly performed in those with ≥3 positive SLNs or after mastectomy (<0.001). In a high-risk subgroup of 31 patients not fulfilling ALND omission criteria, recurrence-free survival did not significantly differ between ALND and non-ALND groups (=0.209, log-rank). Multivariate analysis confirmed that omission of ALND was not an independent prognostic factor for recurrence (hazard ratio=0.29; 95% confidence interval=0.03-2.39; =0.248).

[CONCLUSION] In the era of effective adjuvant radiotherapy and systemic therapy, the indications for omitting ALND may be further extended even to higher-risk patients. These results highlight the diminishing role of intraoperative pathological assessment of SLNB in contemporary breast cancer management.