Causes And Risk Factors for Colon Cancer

Cause of Colorectal cancer:

The exact cause of colorectal cancer is unknown.

Risk Factors

NB: Definitions: (Merriam Webster Medical Dictionary)

Predispose: To make susceptible.
Risk factor: Something which increases risk or susceptibility.

SO, what is the difference between a predisposing factor and a risk factors? Looks the same to me.

Anyway, these are some factors that increase a person's risk of developing the colorectal cancer:

Age. The risk of developing colorectal cancer increases as we age. The disease is more common in people over 50, and the chance of getting colorectal cancer increases with each decade.

Gender. The risk overall are equal, but women have a higher risk for colon cancer, while men are more likely to develop rectal cancer.

Polyps. Polyps are non-cancerous growths on the inner wall of the colon or rectum. Adenomatous polyps increase the risk of developing colorectal cancer.

Past Medical history. Research shows that women who have a history of ovarian, uterine or breast cancer have a somewhat increased risk of developing colorectal cancer. Also, a person who already has had colorectal cancer may develop the disease a second time. In addition, people who have chronic inflammatory conditions of the colon, such as ulcerative colitis or Crohn's disease, also are at higher risk of developing colorectal cancer. The risk for cancer begins to rise after eight to 10 years of colitis.

Family history. Parents, siblings, and children of a person who has had colorectal cancer are somewhat more likely to develop colorectal cancer themselves. If many family members have had colorectal cancer, the risk increases even more. A family history of familial polyposis, adenomatous polyps, or hereditary polyp syndrome also increases the risk.

Diet. A diet high in fat and calories and low in fiber may be linked to a greater risk of developing colorectal cancer. It is believed that the breakdown products of fat metabolism lead to the formation of carcinogens.

Lifestyle factors. You may be at increased risk for developing colorectal cancer if you drink alcohol, smoke, don't get enough exercise, and if you are overweight.

Diabetes. People with diabetes have a 30-40% increased risk of developing colon cancer.
(Read news article on CBS @ http://www.cbsnews.com/stories/2004/10/01/health/webmd/main646860.shtml)


Genetics and colon cancer

A person's genetic background is an important factor in colon cancer risk. Among first-degree relatives of colon cancer patients, the lifetime risk of developing colon cancer is increases threefold.

Even though family history of colon cancer is an important risk factor, majority (80%) of colon cancers occur sporadically in patients with no family history of colon cancer. About 5 % of colon cancers are due to hereditary colon cancer syndromes. Hereditary colon caner syndromes are disorders where affected family members have inherited cancer-causing genetic defects from one or both of the parents.

Chromosome damages cause genetic defects that lead to the formation of colon polyps and later colon cancer. In sporadic polyps and cancers (polyps and cancers that develop in the absence of family history), the chromosome damages are acquired. The damaged chromosomes can only be found in the polyps and the cancers that develop from that cell. But in hereditary colon cancer syndromes, the chromosome defects are inherited at birth and are present in every cell in the body. Patients who have inherited the hereditary colon cancer syndrome genes are at risk of developing large number of colon polyps, usually at young ages, and are at very high risk of developing colon cancer early in life, and also are at risk of developing cancers in other organs.

Contributed by John Lee

Sources:
http://www.medicinenet.com/colon_cancer/page2.htm
http://www.webmd.com/colorectal-cancer/guide/risk-factors-colorectal-cancer
http://www3.mdanderson.org/depts/hcc/
http://www2.merriam-webster.com/cgi-bin/mwmednlm