Application Of Sentinel Lymph Node Biopsy In Clinincally N0 Laryngeal And Hypopharyngeal Cancers

OBJECTIVE:To analyze the characteristic of the radioactive lymph node with metastatic disease and to explore the method of the localization of sentinel lymph node(SLN) with radionuclide in N0 clinincally laryngeal and hypopharyngeal cancer. At the same time,To elevate the influence of the different methods of the sentinel lymph nodes(SLN) of SLNB detecting the presence or absence of cervical nodal occult metastases and To search the method of detecting the SLN micrometastasis .METHODS :Fourty-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 (99mTc-SC) was performed and lymph node mapping was performed by lymphoscintigraphy two hours afterward. The SLN was localized by a handheld gamma probe intraoperatively 10-12 hours after the injection, and we defined the radioactive counts of the parotideomasseteric region as backgroud counts.All hot lymph nodes accumulating radioactivity were harvested and initially termed SLN. Selective neck dissections were performed for all patients.The specimen of SLN was sent to the pathologist for the following analysis: formal paraffin embedded section, consecutive section﹑Immunohistochemistry and Reverse Transcription-Polymerase Chain Reaction assay. The results was compared to the remaining lymphadenectomy specimen. Resection of the primary tumour depended on the location and the T classification.RESULTS:SLNs were identified in 41 of 45 patients with 51 necks, SLNs had occult metastases in 13 cases, 15 necks with SLN-positive of these 13 cases, In 11 (73.3%) of these SLN-positive necks, the SLN with the highest counts contained tumor,harvesting the first-three nodes with the highest radioactive counts,which could detect all patients with occult metastatic disease. There was one false negative case,they were found in non-SLNs of neck specimens,Each neck side was considered a single case,the detection rate of SLN micrometastasis with IHC was 10.0%,which was 17.5% with RT-PCR,compared to IHC,the detection rate of SLN micrometastasis was 7.5% higher with RT-PCR,IHC and RT-PC by the consistency checking of Kappa was=0.920(p=0.000), two methods show the right consistency.To prognose the neck condition, the sensitivity of the pathology,IHC and RT-PCR were 78.6%,93.7%,94.7%;the accurate were 94.1%,98.0%,98.0%;the false negative rate were 21.4%,6.3%,5.3%.CONCLUSIONS: Defining the sentinel nodes as the first-three nodes with the highest activity is sufficient to reduce the number of nodes to be resected while achieving an oncologic sound result. Our study shows that the IHC and RT-PCR is more sensitive than the routine pathological method for the detection of micrometastasis and can greatly enhance the efficiency of micrometastases detection in clinically N0 laryngeal and hypopharyngeal cancer.