**5. Oral premalignant lesions**

The transformation of normal oral mucosa in OSCC entities can be linked to the emergence of Pre-Cancerous lesion [36]. This association with several oral mucosa disorders such as oral leukoplakia, oral erythroplakia, oral lichen planus, nicotine stomatitis, tobacco pouch keratosis and oral submucous fibrosis (Table1) could be seen. However, that kind of disorders presents a varied spectrum of malignant transformation potential [37]. Reviewing the clinical features of oral Pre-Cancerous lesions and OSCC, the literature emphatically agrees that the early detection is the most important strategy for diagnosis and prevention of OSCC [37]. Applying this diagnosis strategy the OSCC-patients reduces the treatment in advanced stages, thereby increasing the chances of cure [36]. One of the extensive efforts in the clinical management of patients diagnosed with Pre-Cancerous lesions is to delineate clinical outcome, since it is difficult to separate lesions that follow a benign transformation from the entities that are predisposed to malignant course [38]. However, can be observed only a subset of Pre-Cancerous lesions following the malignant course blowing in OSCC.


**Table 1.** Malignant transformation Potential of *Precancerous Lesions* (adapted from Neville et al. 2009).

The role of HPV in cancer has been exhausted discuss during the recent years. However, HPV in Pre-Cancerous lesions malignant transformation remains under study. Currently, some of the most studied Pre-Cancerous lesions in the literature are: Oral leukoplakia, Oral erythro‐ plakia, Oral lichen planus Oral submucous fibrosis and Smokeless tobacco keratosis. Aimed to understand the malignant potential of theses lesions some author have attempted to relate the disorder progression with HPV malignant mechanism. Even so, the complete knowledge of viral infection and malignant transformation still remains obscure and controversial.
