Optimal number of radioactive sentinel lymph nodes to remove for accurate axillary staging of breast cancer

BackgroundAlthough sentinel lymph node (SLN) biopsy is the standard technique for staging the axilla of clinically node-negative breast cancer, the optimal number of radioactive SLNs to remove to ensure accuracy and minimize morbidity is still actively debated. The purpose of this study was to determine the minimum number of SLNs to excise to ensure accurate axillary staging of SLN-positive patients.MethodsA total of 126 patients with invasive breast cancer underwent SLN biopsy by periareolar injection of radiolabeled technetium sulfur colloid on the day of surgery. The sequence in which SLNs were removed and the corresponding ex vivo radioactive counts were recorded. SLNs were removed until radioactive counts in the axilla were less than 10% of the ex vivo counts of the hottest SLN.ResultsA radioactive SLN was identified in every patient. The mean number of SLNs identified was 2.86 (range, 1–8). Clinicopathologic features associated with a positive SLN included a palpable tumor (P = .0035), increasing tumor size (P = .0039), increasing histologic grade (P = .0234), and angiolymphatic invasion (P < .001). The highest radioactive counts were found in the first node in 100 patients (79.4%), the second node in 15 (11.9%), and the third or later node in 11 patients (8.7%). Among the 38 patients with a positive SLN (30.2%), the hottest node was the first positive SLN in 27 patients (71.1%). The first positive SLN was the first node removed in 31 patients (81.6%) and after the second node in 37 patients (97.4%); it was removed in all patients by the third SLN.ConclusionThese data support the trend of limiting SLN biopsy to 3 lymph nodes. Removing all SLNs with radioactive counts greater than 10% of the ex vivo counts of the hottest SLN did not increase accuracy.