الفهرس 
Etiology of OSCCOnly 14 pages are availabe for public view
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Abstract
OSCC is extremely destructive locally whereas secondary deposits in the nodes of the neck are a variable feature. Unfortunately, the survival of the patients with OSCC has not been improved in the last 30 years and it is still showing a 5- year survival rate lower than 50%. Tumor hypoxia is a common feature of many cancers and it essentially occurs when the growth of a tumor outstrips the accompanying angiogenesis. An adaptive response of the tumor cells to hypoxia occurs with mainly the expression of HIF-1α that is sensitive to oxygen levels and degraded rapidly under normoxic conditions. Thus, HIF-1α may help critical steps in tumor growth and progression by enabling cells to overcome oxygen deprivation. Angiogenesis is a crucial process to sustain tumorigenic potential in neoplasms. VEGF is the main factor promoting this process by acting directly on endothelial cells. NO is another potent vasodilator and angiogenic factor produced in large amounts by the activity of iNOS. Till now, OSCC progression and the behavioral difference between C-OSCC and its variant VC still attract the attention for more explanation. Thus a novel molecular predictor of malignant progression is needed.This work aimed to investigate the expression and distribution patterns of HIF-1α, VEGF and iNOS in OSCC and to assess the relation between their expressions and clinical stages and histopathological grades of OSCC. Furthermore, the aim was directed to correlate the expression of HIF-1α with tumor angiogeneic activity assessed by VEGF and iNOS immunostaining.