Cancer stem cells and field cancerization of oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) has a high propensity for local failure, which is attributed to recurrence at the primary site or the development of second primary tumors (SPT). Field cancerization that refers to the existence of transformed cells in areas adjacent to the primary tumor, has been attributed to be one of the probable reasons underlying disease relapse. The carcinogenic process necessitates multiple molecular events for the transformation of a normal cell into a cancer cell. This implies that only the long-time residents of the epithelium, such as the stem cells, might be the candidates capable of accumulating these genetic hits. These transformed stem cells- the 'Cancer stem cells' (CSCs), are further known to be equipped with the properties of tumor initiation and migration, both of which are essential for orchestrating field cancerization. The concept that the CSCs might be responsible for field cancerization in OSCC has not been explored extensively. If the role of CSCs as the primary units of field cancerization process is established, their presence in the mucosa adjacent to the tumor may be an indicator for local recurrence and/or development of second primary tumors. In this review, we examine the available evidence in literature exploring the possibilities of CSCs driving the process of field cancerization and thereby being the underlying mechanism for disease recurrence and development of SPT.