What Are the Causes and Risk Factors of Colon Cancer?
CancerColon Cancer

What Are the Causes and Risk Factors of Colon Cancer?

What Are the Causes and Risk Factors of Colon Cancer?
Everyday Health
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Updated on February 26, 2026
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Colorectal cancer, or cancer that starts in either the colon or the rectum, is becoming increasingly common among people younger than 50. Scientists are still working to understand what causes healthy cells in the colon and rectum become cancerous, and then potentially grow and spread uncontrollably.

But researchers do know that colorectal cancer is a result of damage to a cell’s DNA, resulting in genetic changes called mutations.

A small percentage of mutations capable of causing colorectal cancer are inherited, meaning passed along in families. Most, however, are acquired, meaning they develop during a person’s life, possibly because of environmental or lifestyle factors.

For the majority of people who develop colorectal cancer, there’s no single genetic pathway to disease. Scientists are working to better understand the complex interplay of factors that cause this cancer, along with risk factors you can and can’t control (in certain ways, at least). That said, it is imperative for all people to follow current recommendations for routine cancer screening like colonoscopy, regardless of any healthy lifestyle adjustments. The U.S. Preventive Task Force (USPTF) outlines that adults between 45 and 75 years be screened.

 It’s important to discuss the best plan for you with your healthcare provider.

Inherited Causes of Colon Cancer

A small number of people will inherit genetic mutations from their families that dramatically raise their risk for colorectal cancer. They generally develop certain syndromes (sets of symptoms) connected with this genetic legacy.

According to the American Cancer Society, these genetic findings include:

  • Familial Adenomatous Polyposis (FAP), Attenuated FAP (AFAP), and Gardner Syndrome These conditions relate directly to the inheritance of a mutated APC gene. When functioning properly, APC serves as a brake on cell growth. When mutated, it becomes part of a biochemical chain reaction that leads to the formation of hundreds of polyps in the colon that can become cancerous.
  • Lynch Syndrome (Hereditary Nonpolyposis Colon Cancer, or HNPCC) This is an inherited cancer syndrome that raises the risk for many cancers, including colorectal cancer.

     Mutations generally occur in the MLH1, MSH2, MSH6, PMS2 or EPCAM genes. These genes are involved in DNA repair. When they’re mutated, they are not able to prevent mutations that can lead to cancer.
  • Peutz–Jeghers Syndrome Mutations in the STK11 gene (also referred to as LKB1) cause most cases of this syndrome. When not mutated, the gene prevents cells from growing in a rapid and uncontrolled manner. Uncontrolled growth, in this case, leads to colorectal polyps that can become cancerous.
  • MYH-Associated Polyposis (MAP) Mutations in the MYH gene play a role in how cells identify and correct DNA errors made during cell division, which also contribute to cancer.

Colon Cancer Risk Factors You Can’t Control

Some colon cancer risk factors are not under your control. This list includes the following, according to the American Cancer Society:

Age

While there are a growing number of people being diagnosed with early-onset colorectal cancer, the majority of people with the disease are older than 50.

Personal or Family History

If you have had colorectal polyps (abnormal growths in the colon or rectum), you are more likely to develop colorectal cancer. This is especially true if the polyps are big, appear in multiples, or contain cells with precancerous abnormalities (dysplasia).

A family history of colorectal cancer is another risk factor. One out of three people diagnosed with colon cancer or rectal cancer have family members with the disease.

Having had colorectal cancer makes you more likely to get it again, even if you were successfully treated the first time.

A Personal History of Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis, causes chronic inflammation of the colon. This can lead to dysplasia, which may eventually become cancer.

African American or Eastern European Jewish Heritage

Black adults have one of the highest rates of colorectal cancer of any racial group in America. While the USPSTF recommends all adults begin screening at age 45, it underscores the importance of doing so for Black adults, who are at an elevated risk based on disease incidence.

Jewish people of Eastern European descent, called Ashkenazi Jews, are also at high risk compared with other ethnic groups.

Type 2 Diabetes

People with this form of non-insulin-dependent diabetes not only face a higher risk of colon cancer and rectal cancer, they tend to have a less favorable prognosis after diagnosis.

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Risk Factors Under Your Control

Not all cancer risk factors are fixed. Some that you can change (at least theoretically) with lifestyle modifications include the following, according to the American Cancer Society:

Excess Weight

Men and women who are overweight or obese face an increased risk of colorectal cancer. Men, especially those who amass extra pounds around their midsection, are the most vulnerable.

Increasing rates of colorectal cancer among younger people may also be due to rising obesity rates.

A meta-analysis of 66 studies, published in 2024, concluded that overweight and obesity carry an overall increased risk factor for colorectal cancer of 36 percent, which might be slightly more pronounced for men.

A Sedentary Lifestyle

There’s a solid body of evidence connecting a sedentary lifestyle with an increase in colorectal cancer risk and rectal cancer risk.

A cross-sectional study published in 2022 of more than 33,000 participants found an association between sedentary behavior and colorectal cancer risk. The study concluded that colorectal cancer risk was higher among people who practice sedentary behaviors in addition to lacking any physical activity.

A Meat-Heavy Diet

Research associates diets high in red and processed meat (certain lunch meats, hot dogs, sausages) with an increased risk of colorectal cancer among other forms of cancer, according to the American Cancer Society.

 Furthermore, processed meat is a carcinogen and red meat is a probable carcinogen. Carcinogens are substances highly associated with an increased risk of cancer.

Research supports the notion that lowering your intake of red meat can likewise lower your risk of colorectal cancer. A study published in 2025 concluded that replacing red meat with white meat was associated with a lower incidence of colorectal cancer. Processed meat carried a higher cancer risk than unprocessed meat as well, according to results.

Alcohol Consumption

Researchers have found an association between moderate to heavy alcohol use and higher risk of cancers of the colon and rectum. More evidence is needed to better understand whether reducing or discontinuing alcohol use can lower the risk of colorectal cancer.

Smoking

Most people know that smoking raises lung-cancer risk. But there’s less awareness that research also suggests smoking increases colorectal cancer risk for both men and women.

The Takeaway

  • Colorectal cancer describes cancer that starts in either the colon or the rectum. It starts as a result of damage to a cell’s DNA, which leads to mutations.
  • The causes and risk factors of colon and, more broadly, colorectal cancer are the ongoing subject of research. However, scientists know there are certain genetic causes in addition to both unmodifiable and modifiable risk factors.
  • Inherited causes of colon cancer typically include genetic mutations. Risk factors you can’t control include age, family history, and heritage, among others. Risk factors you can (at least partially) control include excess weight, a meat-heavy diet, and avoiding a sedentary lifestyle, among others.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Colorectal Cancer: Screening. U.S. Preventive Services Task Force. May 18, 2021.
  2. What Causes Colorectal Cancer? American Cancer Society. January 29, 2024.
  3. Gomez-Molina R et al. Lynch syndrome and colorectal cancer: A review of current perspectives in molecular genetics and clinical strategies. Oncology Research. June 26, 2025.
  4. Colorectal Cancer Risk Factors. American Cancer Society. April 29, 2025.
  5. Zarefsky M. Colon cancer becoming more common in people under 501. American Medical Association . July 24, 2025.
  6. Matis T et al. Founder pathogenic variants in colorectal neoplasia susceptibility genes in Ashkenazi Jews undergoing colonoscopy. BJC Reports. March 5, 2024.
  7. Ungvari Z et al. Overweight and obesity significantly increase colorectal cancer risk: a meta-analysis of 66 studies revealing a 25–57% elevation in risk. GeroScience. October 8, 2024.
  8. An S et al. Association of Physical Activity and Sedentary Behavior With the Risk of Colorectal Cancer. Journal of Korean Medical Science. May 10, 2022.
  9. Red and Processed Meat and Cancer. American Cancer Society. October 20, 2025.
  10. Carcinogens. Cleveland Clinic. June 19, 2023.
  11. Zouiouich S et al. Meat Consumption in Relation to Colorectal Cancer Incidence in Anatomical Subsites in the National Institutes of Health-AARP Diet and Health Study. Current Developments in Nutrition. September 2025.
  12. O’Connell C et al. Association of alcohol intake over the lifetime with colorectal adenoma and colorectal cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Cancer. January 26, 2026.
  13. Gram IT et al. Smoking-Related Risks of Colorectal Cancer by Anatomical Subsite and Sex. American Journal of Epidemiology. January 23, 2020.
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