Indications and technique of sentinel lymph node biopsy in breast cancer using 99m-technetium labeled tin colloids

The status of the sentinel lymph node (SLN) can reflect the status of other lymph nodes in breast cancer. The efficacy of dye injection and radiolabeled tin colloids for the accurate identification of the SLN was investigated. The indications for SLN biopsy for determining clinical nodal status were also investigated.

A total of 108 patients with breast cancers less than 5 cm were enrolled. Ninety-six patients were clinically node negative and 12 were node positive. About 2 hours before surgery, 1 to 2.5 ml of 99m-technetium-labeled tin colloid was injected around the tumor. Just before the operation, dye was also injected into the tissue surrounding the tumor. Six clinically node negative patients were omitted from the dye-injection process. The SLN was identified as a lymph node with extremely high radioactivity using a gamma probe or a gamma counter. Complete axillary dissection was performed and the metastatic status investigated by hematoxylin and eosin staining.

In clinically node negative patients undergoing dye-injection, the SLN was identified in 89 of 90 patients (98.9%), and there was only one patient with lymph node metastasis outside the SLN. However, in clinically node positive patients undergoing dye-injection, the identification rate of the SLN was 66.7% (8 of 12 patients) and there was one patient with lymph node metastasis outside the SLN (12.5%). Without dye-injection, the SLN could be detected in 4 of 6 patients (66.7%).

Successful identification of the SLN with tin colloid requires concomitant dye-injection and candidates for SLN biopsy should be restricted to clinically node negative cases.