Diagnostic accuracy of sentinel lymph node biopsy in clinically early-stage (cT1-2N0) oral tongue squamous cell carcinoma: A prospective study

Background Accurate staging of the clinically node-negative neck remains a major challenge in clinically early-stage (cT1–T2N0) oral tongue squamous cell carcinoma (OTSCC). Sentinel lymph node biopsy (SLNB) has emerged as a less invasive alternative to elective neck dissection (END), the feasibility and diagnostic accuracy of methylene blue dye as a single tracer remain inadequately defined. Methods This prospective study included 51 patients with cT1–T2N0 OTSCC. All patients underwent SLNB using methylene blue dye as a single tracer, followed by ispilateral selective neck dissection of levels I–III. Sentinel lymph nodes (SLNs) were assessed intraoperatively by frozen section and definitive histopathology. Histopathological findings from the neck dissection specimen served as the reference standard. Diagnostic performance parameters of SLNB were calculated. Results SLNs were successfully identified in all patients, resulting in a 100% identification rate. The mean number of SLNs harvested per patient was 2.18 ± 1.46, most commonly located at level IIA. Occult cervical metastasis was detected in 9 patients (17.6%). SLNB correctly identified 8 of 9 patients with nodal metastasis and 42 of 42 node-negative patients. One false-negative case was observed, while no false-positive results occurred. Accordingly, SLNB demonstrated a sensitivity of 88.9%, specificity of 100%, positive predictive value of 100%, negative predictive value of 97.7%, and overall diagnostic accuracy of 98.0%. Increasing depth of invasion was significantly associated with cervical nodal metastasis (p = 0.019). Conclusions Methylene blue-guided SLNB was feasible and showed a high negative predictive value in this cohort of clinically early-stage (cT1–2N0) oral tongue squamous cell carcinoma. Depth of invasion was significantly associated with cervical nodal metastasis. Larger multicenter studies with standardized pathology protocols and long-term follow-up are needed before this approach can be recommended more broadly.