Sentinel Lymph Node Biopsy Versus Elective Neck Dissection in Carcinoma of the Tongue and Floor of the Mouth

<b>Background/Objectives:</b> Lymph node metastases represent the most important prognostic factor for survival in patients with localized squamous cell carcinoma (SCC) of the oral cavity. In patients with carcinoma of the tongue or floor of the mouth, elective neck dissection (END) has been the standard of care, but it has been replaced at many centers by sentinel lymph node biopsy (SLNB). This study's purpose was to measure and compare recurrence rates between END and SLNB in patients with early SCC of the oral cavity. <b>Methods:</b> Patients were included in this retrospective monocenter cohort study, performed at the University Hospital of Zürich, if they underwent either END or SLNB for oral squamous cell carcinoma (OSCC) of the tongue or floor of the mouth between January 2008 and December 2018. Only patients with early-stage tumors and a clinically negative neck (T1 or T2; cN0) who had a follow-up period of at least 5 years were included. Patients with a T3 or T4 tumor or a clinically positive neck were excluded, as were those who previously underwent therapy for another head and neck carcinoma. The predictor variable was the surgical treatment used, with subjects divided into two groups: END and SLNB. The main outcome variable was the time to recurrent disease, defined as the time between the primary surgical treatment and the diagnosis of recurrence. The covariates were primary tumor location, pT status, pN status, histopathological grade and postoperative radiotherapy. We used descriptive analysis, univariate analysis and the logrank test, with a <i>p</i>-value < 0.05 considered statistically significant. We deliberately refrained from multivariate analysis due to insignificant statistical results in the univariate analysis. <b>Results:</b> In total, 82 patients (46 male, 36 female; median age at the time of surgery: 58.9 years) were included, with a median observation period of 4.3 years. The main primary tumor location was the floor of the mouth (62.2%). The SLNB cohort had smaller primary tumors in comparison to the END cohort (20% vs. 37% pT2, respectively). Furthermore, pN+ disease was more prevalent in the END group in comparison to the SLNB group (81.8% vs. 74.1% pN0, respectively). Recurrence-free survival was not significantly different between the two groups. Subgroup analysis demonstrated a higher risk of recurrent disease in pN+ groups undergoing SLNB compared to those undergoing END. <b>Conclusions:</b> We demonstrate that SLNB is a useful tool for assessing lymph nodes of the neck. In cases of pN+ necks after SLNB and subsequent neck dissection, patients need to be closely followed up with due to the risk of recurrent disease.