الفهرس 
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Abstract
Lung Cancer Ranks Among The Most Common And Most Lethal Malignancies Worldwide. It Is The Leading Cause Of Cancer-Related Death Worldwide (Jemal Et Al, 2005). The High Rate Of Mortality Results from Both The High Rate Of Incidence And The Late Stage Of Disease At Diagnosis. Patients With Non-Small Cell Lung Cancer (NSCLC) Are Frequently Accompanied By Metastasis To Regional Lymph Nodes And Distant Organs. A High Recurrence Rate After Surgical Resection Of Lung Cancer Is Attributable To Microscopic Metastases Present At The Time Of Initial Diagnosis (Ginsberg Et Al, 1997). This High Metastatic Potential Of NSCLC May Be Due To An Active Angiogenesis Of Tumor, In Which Vascular Endothelial Growth Factor (VEGF) Plays An Important Role. VEGF Is 34 - 42 Kda Multifunctional Glycosylated Dimeric Protein With Structural Homology To Platelet –Derived Growth Factor (Keck Et Al, 1989) & Is Expressed In Six Isoforms Derived By Alternative Mrna Splicing (Houck Et Al, 1991; Park Et Al, 1993; Poltorak Et Al, 1997) I.E. VEGF121, VEGF145, VEGF165, VEGF183, VEGF 189 & VEGF 206, Of Those VEGF165 Is Known To Be The Most Abundant Isoform. VEGF Is One Of The Most Potent Positive Regulators Of Angiogenesis, Which Is A Potent Mitogen And Survival Factor For Endothelial Cells, Vascular Permeability& Capillary Tube Formation. In Addition, VEGF Appears To Play A Pivotal Role In The Maintenance Of Abnormal ”Immature” Tumor Vasculature By Acting As A Survival Factor For Endothelial Cells Under Conditions In Which They Would Otherwise Undergo Programmed Cell Death I.E. Apoptosis (Benjamin Et Al, 1999; Karkkainen Et Al, 2000; Liu Et Al , 2000). In Contrast To The Number Of Studies Reporting An Association Between High Microvessel Density & Greater Incidence Of Metastasis & Decrease Survival, Few Studies Discuss The Role Of VEGF Expression In Predicting The Prognosis Of The Patients With Cancer. Amongst Those Studies, Some Have Indicated VEGF Expression As An Independent Factor In Predicting Patient Prognosis, Whilst Other Reported No Such Association (Choi Et Al, 2001; Brattstrom Et Al, 2004; Bremnes Et Al, 2006)