Prognostic significance of tumor budding in early oral tongue squamous cell carcinoma with shallow depth of invasion.

PURPOSE: This study aims to explore prognostic factors for late cervical lymph node metastasis in oral tongue squamous cell carcinoma (OTSCC) with pathological depth of invasion (pDOI) ≤ 3 mm, which, despite shallow invasion, may still be associated with unfavorable oncological outcomes. We emphasize tumor budding (TB) as a potential risk indicator. METHODS: We retrospectively analyzed 107 patients with pT1–T2N0 OTSCC who underwent primary resection and with confirmed pDOI ≤ 3 mm. Variables associated with late cervical lymph node metastasis were first evaluated using univariate analysis. Significant factors were then tested in a multivariate Cox proportional hazards model. We also assessed whether combining pDOI and TB improved predictive performance. RESULTS: Neck recurrence occurred in 9 patients (8.4%) within 3 years. Multivariate analysis showed that TB ≥ 5 was significantly associated with late cervical lymph node metastasis. The combination of pDOI ≥ 2 mm and TB ≥ 5 improved sensitivity and negative predictive value for identifying high-risk cases. CONCLUSION: In OTSCC with shallow pDOI (≤ 3 mm), TB is a potential risk factor for late cervical lymph node metastasis. Incorporating TB into routine pathological evaluation may improve risk stratification in early-stage cases and inform postoperative surveillance strategies.