Sentinel lymph node radiolocalization in clinically negative neck oral cancer.

Background: The sentinel node concept has become one of the most interesting topics in the treatment of head and neck cancer. The aim of this article is to report the results of our feasibility study and clinical application of sentinel lymph node (SLN) radiolocalization and biopsy in patients with clinically negative neck oral cancer.

Methods: Individuals with previously untreated N0 oral cancer participated in the study. The radioactive tracer used was 99m Tc phytate. Lymphoscintigrams were taken in the feasibility study, and fusion images of SPECT and CT were obtained in the clinical SLN biopsy (SLNB) group. In the feasibility study, metastases to SLNs and other nodes were analyzed in permanent specimens. In the clinical application group, we investigated the comparative effectiveness of multi-slice frozen section analysis and imprint cytology for the intraoperative diagnosis of SLNB.

Results: Fifteen individuals participated in the feasibility study. Six SLNs in five patients were cancer-positive, and two thirds of the SLNs were micrometastases. The SLN concept was established, and SLNs with the highest to the third highest radioactivity reflected the patients' neck status accurately. Twelve patients participated in the clinical application group of SLNB. Intraoperative diagnosis of the three hottest SLNs correctly predicted the neck status of 10 patients. Three patients underwent modified radical neck dissection on the basis of the intraoperative diagnosis of cancer metastasis to SLNs, whereas neck dissections were spared in patients with no evidence of such metastases. There were two false-negative cases. One involved a failure of the intraoperative diagnosis of SLNB, and the other had cancer-negative SLNs and cancer-positive non-SLNs. Considering intraoperative diagnosis, multi-slice frozen section analysis was found to be superior to imprint cytology in its sensitivity, specificity, and overall accuracy on a lymph node basis. No differences were found in any of these indices of intraoperative SLNB on a patient basis. The fusion images of SPECT and CT proved very useful during intraoperative SLNB.

Conclusions: The sentinel node concept was established in the head and neck region. Analyzing the three hottest SLNs suffices to predict a patient's neck status. Multi-slice frozen section analysis was shown to be superior to imprint cytology for detecting micrometastasis to SLN. Intraoperative SLNB based on fusion images of SPECT and CT proved to be an easy, accurate, and reliable method.