Association between sentinel lymph node number and prognosis in cT1-2N0M0 early breast cancer patients with negative sentinel lymph nodes: a single‑center retrospective cohort study

Background Sentinel lymph node biopsy (SLNB) is standard for cN0 breast cancer, but the prognostic impact of the number of excised sentinel lymph nodes (SLNs) remains unclear.Objective To evaluate the association between SLN excision number and long‑term prognosis, short‑term axillary complications, and changes in hematological immune parameters in early‑stage breast cancer patients with negative SLNs.Methods TWe retrospectively included cT1–2N0M0 breast cancer patients treated at our institution (2012–2019) with negative SLNs. Patients were grouped by number of SLNs excised: 1–3, 4–6, and ≥7. The primary outcome was 5‑year disease‑free survival (DFS); secondary outcomes included overall survival (OS), axillary complications (lymphedema, mobility/strength limitations), and changes in immune parameters (NLR, PLR, LMR, SII, SIRI). Multivariable Cox and logistic regression analyses were performed.Results Among 1551 patients, 5-year DFS events occurred in 82 (5.3%) and OS events in 39 (2.5%). Axillary complications were reported in 5.9% (lymphedema), 4.8% (strength limitation), and 2.5% (mobility limitation). After multivariate adjustment, SLN excision number was not significantly associated with DFS (≥7 vs. 1-3: HR=1.02, p = 0.95) or OS (HR=0.91, p = 0.86). Logistic regression showed no significant associations with axillary recurrence or complications. Among immune parameters, only the change in neutrophil-to-lymphocyte ratio (ΔNLR) differed significantly between groups (p = 0.02).Conclusion In this retrospective negative‑SLN cohort, the number of SLNs excised was not significantly associated with 5‑year survival or short‑term axillary complications, suggesting that removing 1–3 SLNs may be sufficient in this patient population.