The effect of depth of invasion and tumour size on risk of neck node metastasis in squamous cell carcinoma of oral cavity: retrospective analysis

Background: oral carcinoma is considered to be loco regional disease which metastasizes to nodal and distant sites. Prognostic factors include size of tumor, nodal status, depth of invasion and various pathological factors. Depth of invasion has been suggestive to have a relationship with the occurrence of cervical metastasis. Aim: To study effect of depth of invasion and tumour size on risk of node metastasis in squamous cell carcinoma of oral cavity. Methods: We retrospectively analyzed the effects of three different variables-tumor size, degree of differentiation, and depth of invasion-on the risk of neck node metastasis in 196 adults who had been treated with surgery for primary squamous cell carcinoma of the oral cavity. Primary tumor depth and other pathologic features were determined by reviewing the pathology specimens. Results: Preoperatively, 140 of the 196 patients were clinically N0; however, occult lymph node metastasis was found in 70 of these patients (36.1%). The prevalence of neck node metastasis in patients with T1/T2 and T3/T4 category tumors was 51.5 and 58.8%, respectively. The associations between the prevalence of neck node metastasis and both the degree of differentiation and the depth of invasion were statistically significant. Conclusion: The prevalence of neck lymph node metastasis in patients with squamous cell carcinoma of the oral cavity increases as the tumour depth increases. It is interesting that tumor size, which is the most important component of the TNM system, was not significantly associated with neck node involvement