Clinicopathological study of tumor depth in tongue squamous cell carcinoma

ObjectiveThe mode of invasion at the very bottom of a tumor is reported to be the key to its prognosis, as this reflects the relationship with between the tumor cells and the interstices of the host tissue. The purpose of this study was to investigate the correlation between tumor depth (M, SM, MP1, MP2) and various clinicopathological factors in tongue squamous cell carcinoma.Patients and methodsThe medical records of 193 tongue squamous cell carcinoma patients treated at our hospital between 2000 and 2010 were retrospectively reviewed. Among them, 25 patients were excluded from the analysis as no invasion of muscle tissue was observed, leaving 168 in total. Tumor depth was defined as that as measured from the surface of the mucosa to the very bottom of the tumor.ResultsSubmucosal invasion (SM) was found in 43 cases, shallow invasion of the muscularis propria (MP1) in 83, and deep invasion of the muscularis propria (MP2) in 42. The 5-year survival rate was as follows: 92% in SM, 95% in MP1, and 87% in MP2. Significant differences were observed in survival rate between primary tumor depth (MP group) and mode of invasion; primary tumor depth (MP1) and degree of differentiation; and primary tumor depth (SM) and cervical lymph node metastasis.ConclusionsThe results suggest that primary tumor depth may be used as a prognostic factor in tongue squamous cell carcinoma.