Evaluation of sentinel lymph node size and shape as a predictor of occult metastasis in patients with squamous cell carcinoma of the oral cavity

The aim of the study was to evaluate sentinel lymph node size as a predictor of metastasis in N0 patients with oral squamous cell carcinoma treated by individual sentinel node biopsy (SNB) guided neck dissection. In addition, to evaluate lymph node shape as an indicator of malignancy. A retrospective study based on data from 50 patients with clinically N0 neck and oral squamous cell carcinoma stage T1-2N0M0, SNB and consecutive neck dissection was performed. Excised sentinel nodes were measured in three axes by the surgeons before undergoing histopathological examination. Measured sentinel node axis lengths were compared with the histopathological results. Data were analysed using Microsoft Excel 2008 for Mac, version 12.0. A total of 167 sentinel nodes was excised with a median of 3.3 per patient. Following SNB 18% of the patients was upstaged at the subsequent histopathological examination. This correlates to 7% of the total number of sentinel nodes. The diameters of all three axes were compared for both negative and positive nodes. The positive nodes were not significantly larger. The sensitivity and specificity of lymph node size as a criterion for staging were calculated at several thresholds. There was no tendency that lymph node shape changed towards spherical when positive for metastases. There is a tendency that the risk of metastases and upstaging increases with increasing maximum and partly minimum diameter. However, in this study it was not possible to establish a suitable threshold level with both high sensitivity and specificity based on size and shape. Other features of the lymph node must be considered if an accurate staging of N0 patients is to be performed.