Sentinel Lymph Node Biopsy in Oral and Oropharyngeal Squamous Cell Carcinoma: Statistical Validation and Impact of Micrometastasis Involvement on the Neck Dissection Decision

Purpose: To evaluate the effectiveness of sentinel lymph node biopsy (SLNB) as an optimal staging method in oral and oropharyngeal squamous cell carcinoma (OOSCC) and the impact of the extent of SLN involvement on the decision for neck dissection (ND). Materials and Methods: A prospective cohort study was performed in 96 consecutive patients with stage T1 to T4N0M0 OOSCC (mean follow-up, 62.9 months). SLN localization was determined using cervical lymphoscintigraphy and single-photon emission computed tomography. Patients underwent SLNB examination and ND. The ND specimen was investigated by hematoxylin and eosin (H& E) staining and the SLNs were investigated using H& E staining and step-serial sectioning and cytokeratin antibodies AE1 and AE3. The statistical study calculated the sensitivity and negative predictive value (NPV). The sample size of 96 patients was calculated for a 95% confidence interval with an accuracy of +/- 2% and an estimated a priori sensitivity of 99% compared with the benchmark. The impact of extent of SLN involvement on the decision for ND was analyzed by chi(2) test. A logistic regression model was used to assess the association of predictor variables with SLN involvement and neck disease. Results: The diagnostic accuracy, sensitivity, NPV, and negative likelihood ratio were 95%, 88%, 94%, and 0.06. The statistical comparison between the extent of metastatic involvement of the SLN and neck disease was important for SLN macrometastasis (odds ratio = 11.9), but not for SLN micrometastasis (odds ratio = 0.93). Conclusions: SLNB examination is an excellent staging method in OOSCC. The present data indicate a very small risk of additional lymph node metastasis with SLN micrometastasis. (C) 2015 American Association of Oral and Maxillofacial Surgeons