Impact of sentinel node navigation technique for carcinoma of tongue with cervical node metastases

We attempted lymph node mapping for clinically positive neck using sentinel node navigation technique. Technetium labeled rhenium sulfide was injected as a radiotracer in 11 patients with squamous cell carcinoma of the tongue. After surgery, the radioactivity and the ratio of metastatic area (RMA) of the removed nodes were measured. Average RMA (57%) of 18 high radioactive metastatic nodes was significantly lower than the RMA (90%) of 16 low radioactive metastatic nodes. Average number of metastatic nodes (4.7 nodes) in the five cases with low radioactive metastatic nodes was significantly larger than that (1.8 nodes) in the six cases with only high radioactive metastatic nodes. There is no accumulation of radioactive tracer if a lymph node is totally or predominantly occupied by metastatic cells. When the sentinel node was mostly occupied by malignant cells, the injected colloid could not flow to the sentinel node and flowed to a different lymph node through another basin. Sentinel node navigation technique can show the actual time of lymphatic flow at the operation of positive neck cases.