The high prognostic value of the histologic grade at the deep invasive front of tongue squamous cell carcinoma

Background: Although many histopathologic factors in squamous cell carcinoma of the tongue predict the prognosis, the major predictive factors have not been identified clearly. This study analyzed the prognostic value of the histologic grade at the deep invasive front of tongue squamous cell carcinoma. Methods: The clinicopathologic features of 124 consecutive patients seen between January 1985 and December 1999 with previously untreated squamous cell carcinoma of the tongue were reviewed. Their mean age was 58.5 years (range: 23–90) and the male–female ratio was 1.8: 1 (79 men and 45 women). There were 41, 40, 30, and 13 cases at stage I to stage IV, respectively. The clinicopathologic factors, especially the histologic grade at the deep invasive front (invasive front grade, IFG), were analyzed to determine factors predicting prognosis. Results: The 5‐year disease‐free survival rate of the patients treated with curative aim only was 66.7%. Clinicopathologic factors significantly associated with the prognosis were T classification, tumor size, stage classification, tumor depth, macroscopic appearance, cervical lymph node metastasis (nodal metastasis), microvascular invasion, and IFG. In a multivariate analysis, patients with tumor depth ≥4 mm, IFG ≥8 points, and nodal metastasis had a reduced disease‐free survival and IFG ≥11 points had a predictive value for nodal metastasis (odds ratio: 7.34; P = 0.0019). Conclusion: This study found that a high IFG malignancy score had a high prognostic value for squamous cell carcinoma of the tongue.