Risk Factors

What are some risk factors?

Risk factors increase the chance of developing a disease. Some common risk factors that increase the chance of developing colon cancer, as well as most cancers in general, include older age, ethnicity, a poor diet, alcohol consumption, smoking, obesity, diabetes, lack of exercise, radiation therapy, low Vitamin D intake, genetics, and specific professions. Inflammatory intestinal conditions (e.g Crohn’s disease), a personal history of polyps, or a family history of colon cancer or adenomatous polyps also increases the risk of getting colon cancer.


Since the mid-1980s, the amount of colon cancer cases has dropped for those over 50 years of age, largely due to better screening. However, among young adults who were born in 1990, the risk of colon cancer for this age group has risen by a dramatic 100% (rectal cancer by 300%). The current theory behind the trend seen in the youth is that the increase is a result of highers rates of obesity.

Today, 90% of colon cancer cases involve people ages 50 or older. In general, older age means a higher risk for cancer due to accumulation of mutations that can give rise to uncontrolled cell growth.

Race and Ethnicity

African Americans make up the highest colon cancer incidents and deaths in the United States. The exact reason is unclear, but it may have to do with socioeconomic factors that prevent proper screening, rather than genetics. The most commonly cited reasons for not getting screened include lack of insurance, inability to pay, lack of awareness, and cultural or linguistic barriers.

* Rate per 100,000 population. Rates are the number of deaths per 100,000 persons and are age-adjusted to the 2000 U.S. standard population

Alcohol Consumption & Smoking

Cigarette smoke consists of carcinogenic chemicals that damage or destroy the cells in your body, which can gradually cause the cells to act abnormally. Alcohol consumption can affect the body’s ability to absorb nutrients. Furthermore, bacteria subsiding in the colon and rectum can convert alcohol into a lot of acetaldehyde, a chemical that has caused cancer in lab animals.

Western Diet

Epidemiologists have found links between the Western diet and the manifestation of colon cancer. Current research is looking into whether a fat concentrated, low fiber diet changes the environment inside the colon in which microbes thrive or causes inflammation to the colon wall, perhaps contributing to or causing colon cancer.

Interestingly, compared to people of the same ethnicity living in their native countries, those who have immigrated to America have a higher risk for colon cancer. In fact, a study showed that African natives who switched to an American diet had inflammation in their colon within two weeks.

Obesity & Diabetes II

Insulin resistance – an effect of Diabetes II – encourages an increase in free IGF-1 factors (insulin-like growth factor 1), which can result in excessive cell development and decreased cell death. Both of these results are hallmarks of cancer.

With obesity, the hormone, guanylin, may be missing so that it cannot activate guanylyl cyclase. Since guanylin is essential to ensuring that intestinal epithelial cells are doing their job, intestinal epithelial cells without guanylyl cyclase activation may be more susceptible to becoming cancer cells.

In addition, people with type II diabetes and obesity have increased serum leptin levels, which may increase the chances of getting colorectal cancer. Some research indicates that serum leptin levels influence the development of epithelial intestinal cells (cells on the surface of the small or large intestine).

Radiation Therapy

Previous treatment for a cancer using radiation can damage the DNA in cells and lead to a second cancer. In general, any form of high-energy radiation, such as such as x-rays, gamma rays, alpha particles, beta particles, and neutrons are harmful for the body.

Lack of Vitamin D

For years, Vitamin D has been known to be critical in mineral and bone homeostasis. Recent studies on Vitamin D indicate that it may also have an important role in prevent and treatment of cancer, including colon cancer. Even with adequate sun exposure, 95% of Americans are deficient in this vitamin.


Occupational cancers, cancers that are a result of certain jobs that expose workers to carcinogens, account for 4% of all cancers.

Compared to the general population, firefighters are at a greater risk for developing colon cancer. The largest firefighter study done in the U.S. collected records from more than 30,000 active firefighters from Philadelphia, San Francisco, and Chicago Fire Departments between 1950 and 2010. Their findings indicated firefighters are at a higher risk for colon cancer compared to other people.

This increased risk seen in firefighters is primarily due to their continuous exposure to carcinogens such as benzene, diesel engine exhaust, chloroform, soot, styrene and formaldehyde, which can be absorbed through the skin or inhaled into the lungs.


Personal History of Polyps or Cancer

Family History of Adenomatous Polyps

Personal History of Inflammatory Bowel Disease

For the most part, colon cancer occurs by chance (sporadic) and is not due to inherited genetic conditions. However, having a genetic condition can significantly increase the risk of having colon cancer. The two most common forms of inherited colon cancer syndromes are hereditary nonpolyposis colorectal cancer and familial adenomatous polyposis

Hereditary nonpolyposis colorectal cancer (HNPCC):Also known as Lynch syndrome, HNPCC increases the risk of colon cancer by 40% to 80%. Lynch syndrome is one of the most common hereditary cancer syndromes, with belief that 1 in every 300 people carry a mutation in a gene associated with the syndrome. Those with HNPCC often develop colon cancer prior to turning 50. Some mutated genes that are often associated with Lynch syndrome include MLH1, MSH2, MSH6, PMS2, and EPCAM. Lynch syndrome follows an autosomal dominant inheritance pattern, so only one copy of a mutated gene is needed to inherit the condition. Some people will develop changes in these genes because of the aging processes and other causes unrelated to inheritance. It is estimated that Lynch syndrome accounts for about 3% to 5% of all cases of colon cancer. Your doctor will use a blood test to look for alterations in genes associated with Lynch syndrome.

Familial adenomatous polyposis (FAP):FAP is rare, occurring in one to 22,000 and up to one in 7,000 people according to some estimates. It causes thousands of polyps in the lining of the colon and rectum, with the development of polyps beginning in the mid-teenage years. Left untreated, there is almost a 100% chance one will develop colon cancer. FAP is caused by a mutation in at least one copy of the APC (adenomatous polyposis coli) gene, following an autosomal dominant inheritance pattern. Your doctor will diagnose you with FAP when he or she finds more than 100 polyps or a blood test confirms a mutation in the APC gene.