Oral Squamous Cell Carcinoma (OSCC) has a relatively unfavorable prognosis with a 35% to 50% of 5 year survival. The TNM (Tumor, Node, Metastasis) classification is a commonly used staging system for the Prognostic evaluation for OSCC is mainly based on clinical features, but this staging system supplemented by grading system is required for correct prognostic evaluation. In an attempt to predict the clinical behavior of SCC, the histologic grading of tumors has been used for many decades. SCC's usually reveal a heterogenous cell population with potential differences in invasiveness and metastatic behavior , therefore the initial grading systems like Broderís that classified OSCC into well, moderate and poorly differentiated based on the histologic parameters alone showed a lack of correlation with the prognosis. Therefore, multifactorial grading systems which were mainly based on different parameters of tumor cells as well as tumor-host relationship were introduced.
Our article is an attempt to analyze the historical evolution of these grading systems, summarize and compare each of them and finally determine the most predictive grading systems for the clinical behavior and outcome of Oral Squamous Cell Carcinoma.
Key words: Oral Squamous Cell Carcinoma, staging system, heterogenous cell, multifactorial, parameters, tumor-host relationship.