321P - Sentinel lymph node biopsy in clinical T3-4c breast cancer: A retrospective multicenter cohort study

Background

Sentinel lymph node biopsy (SLNB) has become a standard practice for avoiding axillary lymph node dissection (ALND) in breast cancer (BC) patients without clinically evident axillary metastasis, primarily validated for tumors classified as cT2 or smaller. The applicability and safety of SLNB in more advanced stages, specifically in cT3 and cT4, remain underexplored.

Methods

This retrospective, multicenter observational study included patients with cT3-4cN0M0 BC who underwent radical surgery from 2006 to 2016. We divided the participants into two groups: the SLNB group, where ALND was performed only if the SLNB was positive, and the ALND group, where patients underwent ALND without performing SLNB. Patient characteristics were balanced using the inverse probability treatment weighting (IPTW) method to ensure comparability. The primary endpoint analyzed was recurrence-free survival (RFS), with secondary endpoints including overall survival.

Results

The study cohort comprised 930 patients, with 716 in the SLNB group and 214 in the ALND group. The ALND group had a higher proportion of patients diagnosed earlier (54% from 2006 to 2010, compared to 29% in the SLNB group), more T4 tumors (57% vs. 29%), a greater incidence of metastasis in more than four nodes (15% vs. 9%), and more frequent use of preoperative chemotherapy (72% vs. 31%). The 179 RFS events were observed during 82 months median follow-up period. The 10-year RFS for ALND and SLNB groups was 72.7% and 79.6%, respectively. After adjusting for confounding factors using IPTW, RFS for the ALND group did not demonstrate statistically significant superiority over the SLNB group, with a hazard ratio of 1.16 (95% CI: 0.49-1.51). Detailed analysis showed that the adjusted hazard ratios for RFS did not differ significantly in the ad-hoc subgroup analysis of tumor stage (cT3 or cT4).

Conclusions

Our findings suggest that SLNB is a safe method for axillary staging in patients with advanced BC (cT3-4cN0M0) and does not negatively impact RFS compared to ALND. This supports the potential extension of SLNB to higher stages of BC, encouraging the conduct of further prospective studies to confirm these results and assess long-term outcomes.

Clinical trial identification

Editorial acknowledgement

In preparing the abstract for this work, the authors utilized ChatGPT-4 and Grammarly to enhance grammar and refine the text. After employing these tools, the authors meticulously reviewed and revised the content as necessary. We assume full responsibility for the publication's content.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

Y. Sagara: Financial Interests, Personal, Invited Speaker: Sysmex. T. Sakai: Financial Interests, Personal, Invited Speaker: Exact Science, Canon, Ethicon. All other authors have declared no conflicts of interest.