Cancer of the colon and rectum (colorectal cancer) is a major cause of cancer-associated morbidity and mortality world-wide. It has been suggested that carcinogens introduced into the bowel act in concert with other luminal factors (e.g., bile acid and other tumor promoters) to affect epithelial cells in the colonic mucosa. Carcinogenesis is, however, a multistage process. Cells must be genetically primed (through either hereditary disposition or genotoxic events), must be induced to proliferate and must pass through a series of stages en route to immortalization and uncontrolled growth. Specific molecular changes related to enhanced cancer stage and metastatic potential have been identified. The diagnosis of colorectal neoplasms relies on screening strategies in patients without symptoms. These include the use of fecal occult blood testing with or without screening flexible sigmoidoscopy, radiological procedures or screening colonoscopy. Patients with symptoms of iron deficiency anemia, rectal bleeding or changes in bowel habits should be evaluated by colonoscopic examination. Treatment of colorectal cancer is by excision, either by colonoscopy for early lesions or by surgical means. Patients with evidence of extension of rectal cancer into the bowel wall or lymph nodes are treated with adjuvant chemo- and radiation therapies. Patients with colon cancer and regional lymph node métastases are treated with adjuvant chemotherapy. Chemotherapy of advanced disease has evolved, but is still often palliative. Rapidly evolving knowledge of the pathogenesis of colorectal cancer, especially in high-risk groups, is leading to the development of new tools for identifying which persons will benefit most from cancer surveillance and from adjuvant therapy following potentially curative surgery.
KeywordsColon Cancer Rectal Cancer Bile Acid Fecal Occult Blood Testing Barium Enema
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