RESUMO
BACKGROUND: Tongue cancer comprises 10% of all head and neck cancer, and in spite of progress of therapeutic and diagnostic procedures in oncology, the prognosis of tongue cancer remains poor because of rich lymphatics of the tongue and high propensity of early subclinical lymph node metastasis. MATERIALS AND METHODS: Eighteen cases of tongue cancer specimens were sectioned serially and reviewed to investigate the correlations between macroscopic surface extension diameter and microscopic depth of invasion. And correlations between surface extension, muscular invasion and cervical lymph node metastasis of tongue cancer were studied. Furthermore, safety margin for glossectomy was also studied. RESULTS: The obtained results were as follows: 1) The macroscopic diameter of surface extension and microscopic depth of invasion of tongue cancer were correlated to each other (especially when the macroscopic diameter of surface extension was below 20 mm).2) Surface extension and muscular invasion were correlated independently with cervical lymph node metastasis. However, the 95% confidence index using the Cornfield method was too broad in order to draw a correlation among these three factors. 3) The safety margin was between 2.3mm and 13.5 mm. CONCLUSION: Macroscopic surface extension of tongue cancer serves as a valuable prognostic factor in predicting the depth of muscular invasion. Therefore, the safety resection depth can be estimated by the surface extension. In 12 cases of muscular invasions, relatively high prevalence of cervical lymph node metastasis were found, when compared to that of non-muscular invasive cancer. Therefore, muscular invasion itself is a very useful prognostic factor. But it is difficult to confirm the correlation between muscular invasion and cervical lymph node metastasis because of too broad CI.