Sentinel lymph node biopsy for breast cancer: how many nodes to stop at? Experience at a tertiary centre in Singapore

Objective

Sentinel lymph node biopsy (SLN) using blue dye and radioisotope is a widely used tool in the staging of breast cancer. However, multiple SLNs are frequently found. We sought to determine whether there is safe number of SLNs at which to stop the procedure without affecting accuracy.

Methods

We reviewed the records of 182 patients who underwent successful SLN biopsy using radioisotope and/or blue dye in Singapore General Hospital. SLNs with counts more than 10% of the background axilla count, with retention of blue dye or SLNs that were enlarged were removed and the order of removal recorded. All SLN sites removed were categorized as a dye success, an isotope success or both. The count for each SLN site (if applicable) was recorded.

Results

Seventy-nine percent of the patients who underwent SLN biopsy (144) had multiple SLNs. The mean number of SLNs removed per patient was 2.4. Twenty-six percent of the patients (48) were node-positive. Eighty-five percent of node-positive patients (41) had multiple SLNs. Eighty-eight percent of the node-positive patients were identified within the first two sites, while 97.5% and 100% were identified by the third and fourth sites, respectively.

Conclusion

Seventy-nine percent of patients undergoing SLN biopsy for breast cancer have multiple SLNs. Positive nodes were detected within the first three sites removed in 97.5% of node-positive patients. Terminating the procedure at the third SLN site may help in lowering morbidity and costs without compromising accuracy.