The Correlation between the Depth of Invasion and Occult Lymph Node Metastasis in Anterior Tongue Cancer

Objective: To determine the correlation between invasion depth and occult lymph node metastasis in anterior tongue cancer, and to establish the optimal tumor-depth cutoff that predicts nodal metastasis. Materials and Methods: Retrospective analyses were done for two groups of patients with T1 and T2 clinical N0 oral squamous cell carcinomas of the tongue who were treated between June 1999 and November 2011. Thirty-nine patients were treated with glossectomy coupled with elective neck dissection as a prophylactic measure (the “END group”). Another 10 patients only had glossectomies as their primary treatment, with at least a 2-year follow-up (the “neck-observation group”). Pathological reports were reviewed for the invasion depths at the tongue lesions. Occult cervical node metastasis was defined by node metastasis in neck specimens in the END group, and by recurrence in the neck-observation group. Results: In the END group, the overall lymph node metastatic rate was 30.8% (n=12/39). The mean invasion depth in positive nodal metastasis was greater than in negative nodal metastasis at 8.68±4.3 mm versus 7.66±3.6 mm, but without significance (p=0.44). As to the neck-observation group, the invasion depth of the 10 patients was 2 to 9 mm (mean 4.4±2.32), and cervical lymph node metastasis occurred in 40%. There was a high incidence of occult metastasis for all tumor depths in the END and neck-observation groups, with minimum depths 2 mm, but no significant correlations were found between nodal metastases and tumor depth. Conclusion: There were no correlations between invasion depth and occult lymph node metastasis in T1 and T2 anterior tongue cancers. A high occult-metastasis incidence occurred for all invasion depth with minimal depth 2.0-mm.