Sentinel node biopsy for breast cancer: does the number of sentinel nodes removed have an impact on the accuracy of finding a positive node?

Background And Objectives: The number of sentinel lymph nodes (SLNs) removed during biopsy may have an impact on the accuracy of finding a positive SLN. This study investigated various factors to determine if they had any significant correlation with the number of SLNs found during biopsy. In patients with positive SLNs, the nodes were then analyzed to determine which SLN contained metastasis.

Methods: For 263 patients with breast cancer who successfully underwent SLN biopsy, parameters such as tumor size, histologic characteristics, differentiation, and receptor status, patient age, breast quadrant, type of surgery, mapping with blue dye only or with radiocolloid, and whether biopsy was performed before or after tumorectomy were prospectively collected. These factors were analyzed to determine whether they had any significant correlation to the number of removed lymph nodes. Positive SLNs were ranked in the order they were removed and examined for which node contained the metastasis.

Results: During biopsy, a mean of 1.8 (range, 1-5) SLNs were found. The SLNs were negative in 158 patients and positive in 105. The number of SLNs removed was comparable between node-negative and node-positive patients, and none of the parameters analyzed was significantly related to the number of SLNs removed. Of the 105 patients with a positive SLN, the first SLN independently predicted the pathologic status of the axilla in 96 patients (91.4%; 95% CI 86.1-96.8), and the first and second SLN independently predicted the status in 104 patients (99%; 95% CI 97.2-100). Only one of 105 patients had metastasis in the third SLN removed.

Conclusion: The pathologic status of the axilla was independently determined by removal of the first or first and second SLN in 99% of patients; removal of more than three SLNs did not increase the accuracy of finding a positive node.