Radiolocalization of sentinel lymph nodes in clinically N0 laryngeal and hypopharyngeal cancers.

OBJECTIVES: We sought to analyze the characteristics of radioactive lymph nodes with metastatic disease and to explore methods for the localization of sentinel lymph nodes (SLNs) with radionuclide in clinically N0 laryngeal and hypopharyngeal cancer.

METHODS: Forty-five patients with T1-T4 and clinically N0 laryngeal and hypopharyngeal cancer were recruited. For each patient, a peritumoral submucosal injection of 99mTc-labeled sulfur colloid was administered, and lymph node mapping was performed by lymphoscintigraphy 2 hours after injection. The SLNs were localized during operation by a hand-held gamma probe 10 to 12 hours after the injection, and we defined the radioactive counts from the parotideomasseteric region as background values. All lymph nodes that had accumulated radioactivity were harvested and initially termed as SLNs. Selective neck dissection was performed in all patients. The SLN specimens were sent for formal paraffin-embedded sectioning, serial sectioning, and immunohistochemical assay. The results were compared to those for the remaining lymphadenectomy specimen. Resection of the primary tumor depended on its location and the T classification.

RESULTS: Sentinel lymph nodes were identified in 41 of 45 patients (51 necks). Sentinel lymph nodes with occult metastases were found in 13 patients (15 necks). In a false-negative case, metastasis was found in a nonsentinel lymph node in 1 of the neck specimens. The SLN identification rate was 92.7%, the sensitivity was 93.7%, the false-negative rate was 6.3%, and the accuracy was 98.0%. In 11 of the 15 necks (73.3%) with pathologically positive SLNs, metastasis was found in the node with the highest radioactivity. Harvesting the first 3 nodes with the highest radioactive counts may identify patients with occult metastatic disease.

CONCLUSIONS: Excision of the first 3 SLNs with the highest radioactive counts can be used to accurately identify the status of cervical lymph node metastases in patients with clinically N0 laryngeal or hypopharyngeal cancer.