The Interrelation Among Triad of Depth of Invasion, Perineural Invasion and Tumor Size in Squamous Cell Carcinoma of Tongue and Floor of the Mouth: An Analytical Appraisal.

Background: Head and neck cancer represents 5-10% of all malignancies. Squamous cell carcinoma (SCC) of the oral cavity represents about 2% of overall malignant neoplasms and 47% of the head and neck region Squamous cell carcinoma of tongue has a peculiar behavior of occult and skips metastasis to regional lymph nodes. It occasionally occurs along with floor of the mouth. The purpose of this study is to evaluate the significance of correlation between, depth of invasion of the primary tumor, its proximity with the neurovascular bundle and subsequent perineural invasion and cervical lymph node metastasis in squamous cell carcinoma tongue and floor of the mouth and the sites involving both.

Materials And Methods: A total of 108 patients with carcinoma tongue (59), floor of the mouth (20) and involving both together (29) who underwent treatment during January 2015 to June 2017 that were followed up until December 2019 were assessed. Out of 108 patients that were included in the study, 71 patients underwent primary surgery and 37 patients were inoperable (tongue-17, floor of the mouth-9 and involving both together-11).

Results: Perineural invasion was seen in 15 cases of pT1-2 where depth of invasion was less than 1 cm and in 28 cases of pT3-4 where depth of invasion was more than 1cm (-0.075). Skip metastasis was accounted for 61.9% overall.

Conclusion: The triad of perineural invasion, depth of invasion and tumor size is interrelated and was responsible for cervical lymph node metastasis and prognosis of the disease. Obtaining clear deep margins of the tumor from the mucosal margin and removal of lympho-fatty tissue at the floor of the mouth is an important aspect which gives the indication about prognostic factors like depth of invasion, tumor size, cervical nodal metastasis and recurrence of the disease. High-grade tumors (T3-4), depth of invasion of tumor at 1 cm or > 1 cm, increase the propensity of perineural invasion highly.