Sentinel Lymph Node Biopsy for Early-Stage Oral Cavity Cancer: Analysis of Diagnostic Accuracy and False-Negative Cases.

Background/

Objectives

Identifying the causes of sentinel lymph node biopsy (SLNB) failure in early-stage oral cavity squamous cell carcinoma (OCSCC) is essential for refining surgical protocols and optimizing patient selection. This study aimed to evaluate the diagnostic performance, predictors of false-negative (FN) results, and long-term oncological outcomes of SLNB in patients with early-stage OCSCC.

Methods

A retrospective, single-centre cohort study was conducted on 220 patients with cT1-cT2 N0 M0 OCSCC who were surgically treated between 2017 and 2024. Preoperative lymphatic mapping was performed using 99mTc-nanocolloid and SPECT/CT. All sentinel lymph nodes (SLNs) underwent an ultrastaging protocol involving serial sectioning and immunohistochemistry. Diagnostic accuracy, survival outcomes, and clinicopathological predictors of FNs were analysed.

Results

The SLN identification rate was 99.1%. Metastatic involvement was detected in 49 patients (22.3%), preventing 77.7% of the cohort from undergoing unnecessary neck dissection. Bilateral lymphatic drainage was observed in 55.9% of floor of the mouth tumours. During a median follow-up of 36 months, the diagnostic performance showed a sensitivity of 81.7%, a negative predictive value of 93.6%, and an overall accuracy of 95.0%. Analysis of the 11 FN cases showed that both depth of invasion (DOI) (6.0 mm vs. 3.0 mm; p = 0.010) and maximal tumour dimension (25 mm vs. 15 mm; p = 0.0008) were significant predictors of diagnostic failure. The five-year overall survival rate was significantly superior in patients with negative SLNs compared to the SLN-positive group (82% vs. 61%; p < 0.001).

Conclusions

SLNB is an accurate and reliable staging tool for early-stage OCSCC, providing personalised lymphatic mapping that harmonizes oncological efficacy with the avoidance of overtreatment. However, an increased DOI and a larger tumour size significantly raise the risk of FN events, indicating the need for close postoperative surveillance in these high-risk subgroups.