الفهرس 
Definition of Colorectal CancerOnly 14 pages are availabe for public view
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Abstract
Cancers represent a heterogeneous group of diseases characterized by uncontrolled growth and spread of abnormal cells in the body. The disruptive behaviours of cancer cells reflect dynamic changes in their genomes and in genes that result in disruption of normal regulatory signaling circuits. Cancers vary on the basis of both the biologic features of the disease and the characteristics of the affected organism.
Cancer can be called therefore ”Entropic Disease” since it is associated with the increase of entropy of the organism to the point where the organism cannot correct this itself. External intervention is required to allow the organism to return to a stable entropic state. Although the relatively small risks associated with low-level exposure to carcinogens in air, food, or water are difficult to detect in epidemiological studies, scientific and regulatory bodies throughout the world have accepted the principle that it is reasonable and prudent to reduce human exposure to substances shown to be carcinogenic at higher levels of exposure.
Colorectal cancer (CRC) is one of the commonest cancers and the third leading cause of cancer death. CRC incidence has decreased as a result of effective intervention and life-style changes in the West. The risk of colorectal cancer increases with age; 91% of cases are diagnosed in individuals aged 50 and older. Several modifiable factors are associated with increased risk of colorectal cancer. Among these are obesity, physical inactivity, a diet high in red or processed meat, heavy alcohol consumption, and possibly smoking and inadequate intake of fruits and vegetables.
Colon cancer is cancer that starts in the large intestine or the rectum. Such cancer is sometimes referred to as ”colorectal cancer.”Other types of colon cancer such as lymphoma, carcinoid tumors, melanoma, and sarcomas are rare. The term ”colon cancer” refers to colon carcinoma and not these rare types of colon cancer.
Colorectal cancer ranks second in the terms of incidence and mortality in more developed countries. There is a significant geographical variation in age-standardized incidence rates that vary approximately 20 fold around the world with high rates occurring in countries of Europe, North America, Australia and Japan. Although the colon and rectum have different etiological background, they are usually considered together. Migrants groups from low incidence countries rapidly reach the higher level of adopted country, suggesting that environmental factors play an important role in etiology.
Regular screening examinations by a health care professional can result in the detection and removal of precancerous growths, as well as the diagnosis of cancers at an early stage, when they are most treatable. Cancers that can be prevented by removal of precancerous tissue include cancers of the cervix, colon, and rectum. Cancers that can be diagnosed early through screening include cancers of the breast, colon, rectum, cervix, prostate, oral cavity, and skin. For cancers of the breast, colon, rectum, and cervix, early detection has been proven to reduce mortality.