Invasion and Metastasis of Oral Squamous Cell Carcinoma

Cancer is a hyperproliferative disease and multistage process that involves initiation, promotion and progression of tumor. Tumour or neoplasms originate when they lose their responsiveness to normal growth signals. Neoplastic cells are said to be transformed if they fail to respond normally to signals controlling the cell growth and proliferate excessively in a poorly regulated manner, forming a lump or tissue mass called a neoplasm. Neoplasm can be benign or malignant. Of primary importance in the prognosis of cancer patients is the sequence of events leading to the development of tumor cell invasion and metastasis. The course of tumor metastasis entails a series of stages that lead to the formation of secondary tumors in distant organs and is, largely, responsible for the mortality and morbidity of cancer. Once tumor cells acquire the ability to penetrate the surrounding tissues, the process of invasion is instigated as these motile cells pass through the basement membrane and extracellular matrix, progressing to intravasation as they penetrate the lymphatic or vascular circulation.