The exact cause of colorectal cancer is not known. But there are several risk factors for the disease.
- Other diseases. Colorectal cancer is strongly associated with certain other diseases. Those people considered at high risk include anyone with a personal or family history of colon polyps, inflammatory disease of the colon such as ulcerative colitis or Crohn's disease, and cancers of the pancreas, breast, ovaries, or uterus.
- Heredity. As with any cancer, susceptibility to colorectal cancer is at least partly determined by genetic makeup. A few people inherit medical conditions, such as familial adenomatous polyposis (FAP), MYH-associated polyposis (MAP), Gardner's syndrome, Turcot's syndrome, Peutz-Jagher's syndrome, juvenile polyposis, and Cowden's disease. In all of these disorders, colon polyps develop at an early age and unless treated, these people are almost certain to develop colorectal cancer.
- Hereditary nonpolyposis colon cancer. The disease extends from generation to generation and causes a person to develop colon cancer at a young age with up to 100 colon polyps (which is why it's called “non-polyposis”). This disease is associated with other cancers including endometrial, small bowel, upper urinary tract, bladder, ovary, stomach, bile duct, skin, and some pancreatic cancers. This is known as the Lynch Syndrome.
- Diet. Diet also contributes to the risk of colorectal cancer, although the cause-and-effect relationship is still unclear. People whose diets are high in fruits and vegetables seem to have a reduced risk. Many studies implicate animal fat and protein as promoters of colorectal cancer, although researchers are cautious about drawing any definite conclusions. Some studies show that regularly eating red meat, which is rich in saturated fat and protein, increases risk, while others find no connection. Some scientists think that fat is the main culprit, while others suspect protein. Others contend that it's not the fat and protein themselves, but the way they are cooked. They note that fats and protein cooked at high temperatures -- especially when broiled and barbecued -- can produce a host of potentially carcinogenic substances linked to colorectal cancer.
- Chemical exposure. Heavy exposure to certain chemicals, including chlorine -- which in small amounts is commonly used to purify drinking water -- may increase the risk of colorectal cancer. Exposure to asbestos is thought to be potentially harmful because it has been implicated in causing formation of polyps in the colon.
- History of certain types of surgery. Surgeries like ureterosigmoidostomy, which is performed in the treatment of bladder cancer, and a cholecsytecomy (the removal of the gallbladder). The ladder has been implicated as a risk for colon cancer development in some studies, but not in others.
- History of colon cancer. A prior case of colon cancer increases the risk of a second colon cancer, especially if the first cancer was diagnosed before the age of 60.
- Lifestyle. Smoking and alcohol intake of more than 4 drinks per week increases the risk of developing colon cancer.
- Family history. Those with a first-degree relative with colorectal cancer have an increased risk of the disease. The risk increases if more than one first-degree relative has colon cancer.
- Radiation. Prior radiation increases the risk of cancer to the radiated tissue only.
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Archived: March 20, 2014
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