Long-term outcomes of early stage oral tongue cancer: Main cause of treatment failure and second primary malignancy.

Objective: We attempted to investigate the long-term outcomes, prognostic factors, treatment failures, second primary malignancies, and salvage therapies in early (pT1-2N0) oral tongue squamous cell carcinoma (OTSCC). Methods: We retrospectively analyzed the medical records of 295 early stage OTSCC patients. Results: Two hundred ninety-five patients were enrolled. The average follow-up period was 64.5 months (range, 1-190 months). Five-year recurrence-free survival rate was 84.8% and disease-specific survival rate was 91.2%. On multivariate analysis, only the depth of invasion (DOI) exhibited significant correlations with the disease recurrence. Patient's age and DOI demonstrated a significant association with survival. A total of 53 recurrence and 35 death events occurred, with the main cause of treatment failure being regional or local recurrence. In recurrent cases, the success rate of salvage treatment was 42% at 5 years. During the follow-up period, second primary malignancy occurred in 13 patients, and 8 (61.5%) of those patients were successfully treated. Conclusions: In pT1-2N0 OTSCC, regional or local recurrence is the main recurrence pattern, whereas age and DOI >5 mm are significant prognostic factors related to recurrence and survival. Since several patients experienced second primary malignancies in the head and neck, careful and thorough surveillance may be required to detect second primary lesions. Level of Evidence: 4.