OBJECTIVEThe purpose of this study was to investigate the clinical value of radiolabeled tracer method, methylene blue method and combination of these two methods in detection of sentinel lymph node (SLN), and to evaluate the accuracy of SLN in predicting the cervical lymph nodes status in laryngeal carcinoma patients with clinically negative neck lymph nodes (cN0 ).

METHODSForty-one patients with cN0 laryngeal neoplasms underwent SLN detection using both of radiolabeled tracer and methylene blue. SLN imaging was performed with laryngoscope-guided injection of radioactive isotope 99Tc(m)-sulfur colloid (SC) into the laryngeal carcinoma before surgery, then all these patients underwent intraoperative lymphatic mapping with a handheld gamma-detecting probe. After mapping of SLN, methylene blue was subsequently injected at the same spots around the tumor in order to identify SLN during surgery. The results of SLN detection by isotope tracer, dye and combination of both methods were compared.

RESULTSThe SLN detection rates by radiolabeled tracer, methylene blue and combined method were 87.8%, 70.7% and 92.7%, respectively (P < 0.01). The number of detected SLN was significantly different between radiolabeled tracer method and combined method (P < 0.05), and also between blue dye method and combined method (P < 0.01). However, no statistically significant difference was found between methylene blue method and radiolabeled tracer method (P > 0.05). Nine patients were found to have lymph node metastasis by final pathological examination. The sensitivity, accuracy and negative predictive values of SLN detection by the combined method using radiolabeled tracer and methylene blue were 88.9%, 97.4% and 96.7%, respectively.

CONCLUSIONThe combined method using radiolabeled tracer and methylene blue can improve the accuracy of sentinel lymph node detection. Furthermore, sentinel lymph node detection can accurately predict the cervical lymph node status in cN0 laryngeal carcinoma.