11 Causes of Colon Cancer

Understanding the Risk Factors Allows for Early Diagnosis

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Colon cancer is the second leading cause of cancer deaths in the U.S. with nearly 150,000 cases diagnosed each year. All told, around five percent of American men and women will experience colon or rectal cancer in the course of their lifetime of whom 30 percent will die as a result of the disease.

Early diagnosis is key to treatment success. Despite this commonly known fact, people will resist getting a colorectal exam because they don't believe themselves to be at risk.

To those in doubt about the importance of routine screening, consider the following 11 factors associated with an increased risk of colon cancer:

1. Age and Aging

Age is the number one risk factor for colon cancer with 81 percent of cases occurring in people over the age of 45. Of these, more than 65 percent of cancer will be in persons between the ages of 65 and 84.

2. Alcohol Consumption

The American Cancer Society has cited alcohol as a contributing factor to four different types of cancer, including colorectal cancer. Others include liver cancer, breast cancer, and oral cancers. Risk is directly linked to the amount of alcohol consumed.

3. Diabetes Risk

A study published in the journal Gastroenterology found that insulin dependency contributes to the development of colon cancer. All told, diabetics are up to 40 percent more likely to develop colon cancer compared to people in the general population.

4. Dietary Factors

Diets high in fat and cholesterol, especially from animal sources, have been linked to colon cancer. High-fat foods can change normal cells into stem cells which then have the potential to convert into tumors. A diet low in fiber, fruits, and vegetables is also associated with an increased risk.

5. Ethnicity and Race

Ethnicity is also a well-known factor associated with cancer risk. African Americans, for example, have a 40 percent greater chance of colon cancer than whites, as well as a 20 percent greater risk of death. By contrast, Asians are known to be at lower risk when compared to all other groups.

6. Family History of Colon Cancer

If you have had a relative who had colon cancer, your chance of getting the disease is automatically increased. If it's a first-degree relation (a parent, sibling, or offspring), your risk can double and even triple in some cases.

7. Genetic Factors

Research has shown that one in four cases of colon cancer has some sort of genetic link. The most common hereditary causes include genetic mutations associated with the development of FAP (familial adenomatous polyposis) and HNPCC (hereditary non-polyposis colorectal cancer).

8. Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is characterized by conditions such as ​ulcerative colitis and Crohn's disease. Both are associated with the development of colorectal cancer. Generally speaking, the longer a person has had IBD, the greater his or her chance of developing colon cancer.

9. Obesity and Cancer Risk

The link between colon cancer and obesity is strong.

All told, people who are obese are over 30 percent more likely to develop this type of cancer than people of normal weight

10. Precancerous Polyps

A colon polyp is a small clump of cells that forms on the lining of the colon. Virtually all colon cancers develop from non-cancerous adenomatous polyps that that are similar in structure to normal tissues but can suddenly become malignant as they grow in size.

11. Smoking Risk

We all know that cigarettes can cause damage to every organ system of the body. In terms of colon cancer, long-term smoking is associated the accelerated polyp growth as well the delivery of carcinogens to the mucosal tissues of the colon.

These together create a perfect storm for cancer.

Now that you have a handle on what causes colon cancer, learn the top 10 ways to prevent the disease whether you consider yourself at risk or not.


American Cancer Society. "The Link Between Alcohol and Colorectal Cancer." Atlanta, Georgia; August 25, 2015.

Centers for Disease Control and Prevention (CDC). "What Are the Risk Factors for Colorectal Cancer?" Atlanta, Georgia; updated April 25, 2016.

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