الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Colon cancer is considered the commonest type of cancer of the gastrointestinal tract(GIT). It is a disease process that is characterized by multiple etiological factors that include genetic factors, environmental factors (as type of diet), and inflammatory conditions of the GIT. All over the world, colorectal cancer is estimated to be the 2nd most common type of cancer in females (614,000 patients represent ~9.2% of all cancers) and the 3rd most common in male (746,000 patients representing ~10.0% of the total) Colorectal cancer results in about 694,000 deaths per year, responsible for about 8.5% of cancer mortality worldwide. Indeed, colorectal cancer (CRC) is considered one of the commonest tumors that run in families. It has been postulated by Kindred & twin studies that ~30% of all CRC patients represent inherited form of the disease. About 5% of patients are accompanied by inherited mutations that are highly penetrant as well as well-characterized clinical presentations. However, the etiology of the remaining 20–30% of inherited CRCs patients are not understood, yet.They might result from changes in single genes which are less penetrant but they are more common than those accompanied by the well-characterized syndromes. Sporadic causes might be responsible for > 80% of colorectal cancer, they include Environmental factors, Dietary factors Obesity, Cigarette Smoking, Heavy Alcohol Consumption, Infections, and Inflammation. Typical symptoms and signs that frequently associate CRC include abdominal pain, hematochezia or melena, iron deficiency anemia without obvious cause, and/or a changed bowel habits. Also, patients may less frequently complain from abdominal distention, and/or nausea and vomiting that indicate the presence of obstruction. Recently, occult anemia appears to be more common finding than a changed bowel habits. As an example, in an assembly of the most frequent complains and findings that urged diagnostic colonoscopy.
It has been reported that about 20% of patients at time of presentation in the USA have distant metastasis. Recently, the gene encoding CEA has been categorized as a member of the immunoglobulin supergene family that includes genes encoding for adhesion molecules as intercellular adhesion molecule 1(ICAM-1), the major histocompatibility (MHC) antigens, and lymphocyte function-associated antigen 1. CEA gene family is composed of 29 genes that present on chromosome 19q. 18 of these genes are expressed, with seven of them belonging to the CEA subgroup and the other 11 to the pregnancy-specific glycoprotein subgroup. The American Society of Oncology doesn’t encourage the use of CA 19-9 because it is less sensitive in asymptomatic, unadvanced patients of CRC giving false negative results. Also, it is present in non-cancer patients (false positive). CA 19-9 is less specific in CRC as It may be found in various types of tumors such as pancreatic, gastric cancers, hepatocellular carcinoma, as well as in benign patients as bile duct diseases as obstruction of the bile duct. In addition, subjects who haven’t the Lewis antigen ”(a blood type antigen on RBCs) who represent approximately 10% of the Caucasian population”, not express CA 19-9, even if they have large tumors.CA19-9 could be detected on patient’s blood. Both CEA and CA19-9 biomarkers is considered of prognostic value better than a diagnostic tool. The recurrence of disease locally could be determined on CT by the serial progression of a mass, its nodular appearance and invasion of near by structures. In fact, the inactivation of carcinogenic miRNAs is considered of the new the strategies used in miRNA-based therapeutics.