Colon Cancer Causes, Risk Factors and Prevention

wColon cancer develops when cells lining the large intestine (colon) acquire genetic changes that allow them to grow and divide uncontrollably. In many cases, the mutations begin in precancerous growths called polyps, which can gradually become cancerous over time. Although the exact reason these genetic alterations occur is not always known, researchers have identified several inherited, medical and lifestyle factors that can increase the likelihood of developing colon cancer.

According to the American Cancer Society, colon cancer is the third most frequently diagnosed cancer in both men and women in the United States, excluding skin cancers. While the risk increases with age, rates have risen in younger adults in recent years, underscoring the importance of learning about risk factors, recognizing early signs and following recommended screening guidelines.

What causes colon cancer? 

The inner lining of the large intestine is constantly renewing itself as old cells are replaced with new cells. Colon cancer can develop when genetic changes disrupt the normal processes that regulate cell growth, allowing abnormal cells to continue growing, divide uncontrollably and eventually form a tumor.

In many cases, colon cancer begins as an adenomatous polyp, a benign growth that forms in the glandular tissue of the colon lining. Although not every polyp will become cancerous, some can gradually accumulate additional genetic changes that lead to cancer if they are not detected and removed.

Researchers believe several factors may contribute to the development of colon cancer, including:

• Acquired genetic changes – Most colon cancers result from DNA mutations that occur during a person’s lifetime rather than being inherited. These changes can affect genes that regulate cell growth, repair damaged DNA or prevent abnormal cells from surviving.
• Progression of precancerous polyps – Some adenomatous polyps are more likely than others to become cancerous over time, especially if they are not detected and removed.
• Inherited genetic syndromes – A small percentage of colon cancers are linked to a hereditary condition, such as Lynch syndrome or familial adenomatous polyposis (FAP).
• Long-term inflammation of the colon – Chronic inflammatory conditions affecting the large intestine may contribute to ongoing cellular damage that increases cancer risk.

What are the risk factors for colon cancer?  

Although colon cancer can develop in individuals with no known predisposition, several factors are associated with increased risk, including:

• Increasing age – Colon cancer is diagnosed most often in adults older than 50, although diagnoses among younger adults are becoming more common.
• Personal history of adenomatous polyps or colorectal cancer – Individuals who have previously had certain colon polyps or colorectal cancer are more likely to develop colon cancer in the future.
• Inflammatory bowel disease (IBD) – Long-standing ulcerative colitis or Crohn’s disease involving the large intestine increases the risk of colon cancer.
• Inherited genetic syndromes – Lynch syndrome, familial adenomatous polyposis (FAP) and several other rare inherited conditions can substantially increase colon cancer risk.
• Family history of advanced colon polyps or colorectal cancer – Having a close relative with certain precancerous polyps or colorectal cancer may increase the risk, particularly when multiple relatives are affected or diagnoses occur at younger ages.
• Type 2 diabetes – Individuals with type 2 diabetes have an increased risk of developing colon cancer, particularly when insulin resistance is present.

Which risk factors for colon cwancer are nonmodifiable (factors you cannot control)?

Some risk factors for colon cancer cannot be changed. Understanding these characteristics can help identify individuals who may benefit from earlier screening, genetic counseling or more frequent surveillance based on their personal risk level.

Nonmodifiable risk factors for colon cancer include:

• Age – The likelihood of developing colon cancer increases with age, although younger adults can also be affected.
• Inherited genetic syndromes – Lynch syndrome, FAP and certain other hereditary conditions significantly increase the risk of colon cancer.
• Family history – A family history of advanced adenomatous polyps or colorectal cancer may indicate an inherited predisposition.
• Personal history of inflammatory bowel disease – Chronic ulcerative colitis or Crohn’s disease involving the large intestine cannot be changed and remains an important long-term risk factor.
• Personal history of adenomatous polyps or colorectal cancer – Individuals who have previously developed these conditions remain at increased risk for future colon cancers.

Which risk factors for colon cancer are modifiable (factors you can control)?

Several lifestyle and health-related factors are linked to colon cancer risk. While changing these factors cannot completely eliminate the possibility of developing colon cancer, healthy lifestyle choices may help reduce the risk. Potentially modifiable risk factors include:

• Excess body weight – Being overweight or obese is associated with an increased risk of colon cancer, particularly in men.
• Physical inactivity – Regular physical activity is associated with a lower risk of colon cancer, while a sedentary lifestyle may increase the risk.
• Poor nutrition – Diets high in processed meats and red meat have been linked to an increased risk of colon cancer, while diets rich in fruits, vegetables, whole grains and other fiber-rich foods may help reduce the risk.
• Alcohol consumption – Heavy alcohol use is associated with an increased risk of colon cancer.
• Smoking – Long-term tobacco use increases the likelihood of developing many types of cancer, including colon cancer.

Can colon cancer be prevented?

Although not all cases of colon cancer can be prevented, several strategies may help lower the risk and detect precancerous polyps before they become cancerous. These include:

• Participating in recommended colorectal cancer screenings – Screening can identify and remove many precancerous polyps before they become cancerous.
• Maintaining a healthy weight – Achieving and maintaining a healthy body weight supports overall health and may help lower colon cancer risk.
• Being physically active – Regular exercise is associated with a reduced risk of colon cancer and many other chronic diseases.
• Following a balanced diet – Consuming a diet rich in fruits, vegetables, whole grains and lean proteins while limiting consumption of processed and red meats may support colon health.
• Limiting alcohol consumption – Reducing alcohol intake may help decrease colon cancer risk.
• Avoiding tobacco products – Not smoking benefits overall health and reduces the risk of many cancers, including colon cancer.
• Discussing family history with a healthcare provider – Individuals with a strong family history of colorectal cancer or inherited cancer syndromes may benefit from genetic counseling or earlier surveillance.

Rated High Performing in Colon Cancer Surgery

Recognized in U.S. News & World Report's Best Hospitals for significantly better performance in colon cancer surgery than the national average.

Schedule an Appointment

Frequently asked questionsw (FAQs) about colon cancer causes and risk factors

Colon cancer often develops over many years, and some people may have questions about why it occurs and whether it can be prevented. The following question addresses one of the most common concerns:

• What foods can reduce the risk of colon cancer?

Find the help you need for colon cancer at Moffitt Cancer Center 

Whether you have a strong family history of colorectal cancer or are concerned about other risk factors, the multispecialty team in Moffitt’s Gastrointestinal Oncology Program can evaluate your individual risk profile, recommend appropriate testing and develop a care plan tailored to your unique needs.

If you would like to learn more about colon cancer causes, risk factors, prevention or treatment options, you can request an appointment with a specialist at Moffitt by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.