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Abstract
Colorectal carcinoma is one of the most common neoplasms affecting individuals in most western countries and is the second only to lung cancer as a cause of cancer death (Acikalin et al, 2005). CRC develops sporadically, on the basis of inflammatory bowel diseases and in the setting of hereditary cancer syndromes (Stewart and Kleihues 2003). The adenoma-carcinoma sequence is the basis for development of colorectal cancer, and the underlying molecular changes have largely been identified (Liu and Crawford 2005). The biological behaviour of colorectal carcinoma (CRC) is related to some extent to a number of clinical and pathological parameters that have prognostic value including tumor stage, grade and the presence of vascular invasion (Cooper 2004). Screening and prevention programs are available and should be more widely used (Rudy and Zdon 2000).
VEGF is one of the most important proangiogenic factors, selectively overexpressed in many human cancers but not in normal adult tissues, and is associated with unfavorable outcomes (Acikalin et al, 2005). Studies have shown that anti-VEGF agents radiosenstizes the endothelial cells, so the combination of radiation with anti-VEGF agents increase the antitumor effect of radiation (Lee et alf 2000). Food and Drug Administration (FDA) approved a humanized monoclonal antibody directed against VEGF in combination with intravenous 5-flourouracil based chemotherapy for the 1st line of treatment of patients with
metastatic colorectal carcinoma (Rosen 2005).