Comparative study of sentinel lymph node biopsy in clinically N0 oral tongue squamous cell carcinoma: Long-term oncologic outcomes between validation and application phases

Objective: This study tested the long-term outcomes of sentinel lymph node biopsy (SLNB) for oral tongue squamous cell carcinoma (SCC) during the transition from validation to application phase.

Materials and methods: Sensitivity, negative predictive value (NPV), neck control rate, disease-specific survival (DSS), disease-free survival (DFS), and overall survival (OS) were compared in cN0 oral tongue SCC patients from different phases.

Results: A total of 133 SLNs from 61 patients (21 in the validation phase, 40 in the application phase) were harvested. Fourteen SLNs of 12 patients (6 in each phase) were positive for metastasis (occult metastasis rate, 19.6%). Regional recurrences developed from 5 negative SLNs (one in the validation phase, 4 in the application phase), of whom 3 patients were successfully salvaged. Sensitivity and NPV of the validation phase were both 100%, with 60.0% and 88.2% in the application phase. False omission rates were 6.6% (1/15) in the validation group, and 11.7% (4/34) in the application group, respectively. The neck control rate was 95.2% in the validation phase and 97.5% in the application phase (p=0.52). No differences were evident in DSS, DFS, and OS between the two phases (DSS: 92.5% vs 95.2%, p=0.69; DFS: 85.0% vs 90.4%, p=0.40; OS: 90% vs 85.5%, p=0.62). Subgroup analyses between negative- and positive-SLNs within each phase revealed no significant differences in all endpoints.

Conclusion: Given higher false negative cases in the application phase, stringent strategy of follow-up and salvage treatment is mandatory to maintain acceptable outcomes.