Does the Number of Harvested Sentinel Lymph Nodes Matter in Breast Cancer Patients with Limited Nodal Burden? A Descriptive Cohort Study

Background/Objectives: In breast cancer patients with limited nodal burden, sentinel lymph node biopsy (SLNB) alone, without axillary lymph node dissection (ALND), has shown non-inferior survival. However, it remains unclear how many SLNs should be harvested. We aimed to determine if the number of harvested SLNs and the use of a single agent for SLNB localisation affect the detection of residual metastatic nodes. We also described the oncological outcome of SLNB alone as an exploratory clinical outcome. Methods: From 1 January 2020 to 31 January 2026, T1–2 patients and 1–2 metastatic SLNs who underwent SLNB only or with completion ALND were analysed. The number of SLNs harvested and the use of single or dual agents for localisation of SLNs were analysed in the ALND group to determine if it affected the detection of residual metastatic nodes. Data on oncological outcomes were reported. Results: A total of 152 patients were enrolled, of which 63 and 89 underwent SLNB alone and ALND respectively. The ALND group had more patients with mastectomy (p = 0.0044), macrometastasis (p = 0.0001) and no radiation to the axilla (p = 0.0001). Median number of harvested SLNs was 3 (range: 1–8) and 2 (range: 1–9) in the SLNB and ALND groups respectively. In the ALND group, a mean residual 2.4 metastatic nodes (range: 1–9) was seen in 24.7%. Multivariable logistic regression showed that a higher SLN yield was not associated with less residual disease (adjusted OR 0.71 per additional SLN, 95% CI [0.46, 1.12]). Conversely, the number of metastatic SLNs was statistically associated with residual nodal disease OR 3.6 95% CI [1.19, 10.86]. Single-agent SLNB localisation (mainly patent blue dye) was used in 22% and 19.3% of SLNB and ALND group respectively. Though dual-agent localisation had more patients with ≥ 2 SLNs (p = 0.0181), it was not statistically associated with residual nodal metastatic disease which occurred in 7/17 (41.2%) single-agent versus 15/71 (21.1%) dual-agent cases (p = 0.1184; OR 2.58, 95% CI [0.71, 9.09]). No recurrences were observed on a median follow-up of 37 (range: 3–75) months. Conclusions: The number of harvested SLNs and the use of patent blue dye as a single-agent localisation were not statistically associated with residual nodal disease in patients with limited nodal burden. Instead, metastatic SLN burden was statistically significant for residual nodal disease. However, our findings were limited by small sample size and should be considered as exploratory in nature with validation needed in larger studies with longer follow-up.