The breast cancer patient with multiple sentinel nodes: when to stop?

During sentinel lymph node (SLN) biopsy for breast cancer, most authors report identifying a mean of 1 to 3 SLNs, but a range of 1 to 8 (or more) SLNs per patient. A significant minority of patients have 4 or more SLNs. Here we seek to determine the significance for the breast cancer patient of finding multiple SLNs, and whether there is an optimal threshold number of SLNs that should be removed.

1,561 patients who underwent successful SLN biopsy using blue dye and radioisotope in combination. Each SLN site was categorized prospectively by the operating surgeon as a dye success, an isotope success, or both. All SLNs containing counts at least four times greater than the postexcision axillary background were considered to be isotope successes.

Fifteen percent of patients (241) had multiple (>3) SLNs. Ninety-eight percent of node-positive patients (440 of 449) were identified within the first three SLN sites examined. In 2% of all SLN positive patients (9 of 449) or 4% of patients with multiple SLN (9 of 241), a positive SLN was detected at site four or more. In eight patients the first positive SLN was found at sites four or more. Blue dye and isotope were equally effective in identifying metastases in patients with multiple SLNs.

Fifteen percent of patients having SLN biopsy for breast cancer have multiple SLNs. Although 98% of positive SLNs were identified within the first three sites sampled, a small number of patients had their first positive SLN at sites 4 to 8. These data suggest that there is no absolute upper threshold for the number of SLNs that should be removed. Sampling a few additional SLNs probably adds little morbidity to the procedure, yet may significantly alter the treatment of some individuals. SLN biopsy should be continued until all blue and hot nodes are removed.