Omission of Sentinel Lymph Node Biopsy in Early-Stage HER2+ and Triple-Negative Breast Cancer: A Retrospective Analysis

<b>Background:</b> Sentinel lymph node biopsy (SLNB) is the standard procedure for axillary staging in early-stage breast cancer. However, its necessity for some patient groups is being reevaluated. This change mainly arises from the procedure's impact on quality of life and new evidence suggesting that some patients can forgo it without affecting their overall survival. <b>Objective:</b> This study focuses on the omission of SLNB in elderly patients aged 80 and older with HER2-positive (HER2+) or triple-negative breast cancer (TNBC) who are clinically node-negative (cN0), comparing outcomes to other relevant studies. <b>Methods:</b> In this retrospective study, we analyzed 39 cN0 women aged 80 and older (mean age at surgery 85.8) with HER2+ or TNBC treated between 2016 and 2024. We assessed overall survival (OS), disease-free survival (DFS), and locoregional recurrence without performing SLNB. We used Kaplan-Meier estimates and Cox proportional hazards models to evaluate survival outcomes by subtype, tumor size, and Ki-67 index. <b>Results:</b> The median OS was 3.9 years (95% confidence interval [CI]: 3.1 years, not estimable [NE]); the 5-year OS was 43.4% (95% CI: 25.3-74.6). The 5-year DFS was 37.7% (95% CI: 21.5-66.2). The median follow-up was 36.5 months (approximately 3.0 years). Five recurrences (12.8%) and two complications (5.1%) occurred. Patients with TNBC had a 5-year OS of 58.2% compared with 35.9% in those with HER2+ disease (<i>p</i> = 0.414). Patients with a low Ki-67 index (≤25%) had a 5-year OS of 78.6% compared with 25.9% in those with higher Ki-67 (<i>p</i> = 0.080). Tumor size ≥pT2 was associated with a worse prognosis. <b>Conclusions:</b> In carefully selected elderly patients with HER2+ or TNBC and no clinical nodal involvement, omitting SLNB was not linked to significantly lower survival rates. The observed numerical differences according to Ki-67 and tumor size suggest that surgical de-escalation may be feasible in selected elderly patients to limit complications without compromising oncological safety.