Colon Cancer Prevention and Early Detection

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Doctor and patient

Colon cancer is cancer of the large intestine. Another name for this condition is colorectal cancer. This term includes cancer of the rectum, which is the last six inches of the colon. Colon cancer is the third most common cancer after skin cancer for both men and women. An average American has about a 5% lifetime risk of developing this cancer.

Bleeding and other bowel problems can be some of the first symptoms of colon cancer. However, there may be no early signs of colon cancer and very few symptoms in the early stages of the disease. This is because nearly all colon cancers are adenocarcinomas, which develop slowly over many years. They start as noncancerous polyps in the lining of the colon. Checking for these polyps is a powerful tool doctors have for colorectal cancer prevention and early detection of colon cancer. Finding colon cancer early—or even before it develops in some cases—offers the best chance of successfully treating the disease.

What are the risk factors for colon cancer?

Anyone can get colon cancer, but there are certain factors that increase the risk of developing it. Scientists do not fully understand how or why cancer begins. So not all people with these risk factors will end up with colon cancer. Risk factors for colon cancer include:

  • African American race

  • Age. The risk increases with age, with 90% of colon cancers occurring in people 50 years of age and older.

  • Family or personal history of colorectal polyps or colon cancer

  • Genetics. Up to 10% of colon cancers are related to mutations in genes and genetic syndromes.

  • Personal history of IBD (inflammatory bowel disease), which includes Crohn’s disease and ulcerative colitis

  • Type 2 diabetes

Lifestyle factors, such as obesity, not exercising, smoking, poor diet, and heavy alcohol use can also increase your risk of colon cancer. People who are obese are 30% more likely to develop colon cancer compared to people with a healthy weight. Being overweight increases the risk for both men and women, but it seems to affect men more. Your risk of dying from colon cancer is also higher if you carry extra weight or are obese.

Reducing your risk of colon cancer

Colon cancer prevention relies on the same basic strategies as many other cancers—changing risk factors you can control. For colon cancer, this means making lifestyle changes. You may be able to lower your risk of colon cancer by:

  • Drinking alcohol in moderation or not at all. For men, this means no more than two drinks per day. Women should have no more than one drink per day.

  • Eating a balanced diet. In general, this means increasing your consumption of fruits, vegetables, and whole grains, and limiting red meats and processed meats.

  • Getting regular physical exercise. This means participating in moderate activity most days of the week. A brisk walk qualifies as moderate activity. Increasing the amount and intensity of your activities may have even more benefit for lowering colon cancer risk.

  • Maintaining a healthy body weight. The combination of diet and exercise can help you achieve and maintain this goal.

  • Quitting smoking or not starting. If you struggle with this habit, talk with your doctor about strategies for stopping. And never quit trying to quit.

Everyone should talk with their doctors about colon cancer and ask about their risk. It will help you make informed decisions about your lifestyle. People at high risk of colon cancer may need to take additional steps to protect their health. This includes people with a strong family history of colon cancer, who may benefit from genetic testing. Identifying abnormal genes in your DNA may mean there are other actions you can take to lower your risk. This could include early colorectal cancer screening or surgery in some cases.

Early detection of colon cancer

Ultimately, it is not possible to prevent all cases of colon cancer. You can still develop the disease even if you have no risk factors or you make all the right lifestyle changes. This makes early detection a vital part of battling colon cancer. Finding it early can lead to successful treatment and recovery.

Doctors rely on colon cancer screening exams for early detection. Screening exams look for signs of disease before you have symptoms. For people at average risk of colon cancer, screening should start at age 50. Common screening exams include:

  • Colonoscopy. It is a common colon screening because it allows your doctor to view the entire length of the large intestine. Your doctor can also remove any suspicious areas or polyps to biopsy during the exam. It requires bowel preparation to clean out the colon. You will have sedation to keep you comfortable during the exam. You need this test every 10 years-sooner if suspicious areas or polyps are discovered.

  • CT colonography, or virtual colonoscopy. This colon screening method uses a CT scan to produce detailed pictures of the inside of the colon and rectum. It is necessary to fill the colon with air to do this. Even though it is not invasive like a colonoscopy, your colon must still be clean for the test. This means it uses the same type of bowel preparation. If your doctor sees a potential problem, you will need a colonoscopy to remove the problem tissue. You need this test every five years.

  • Stool tests. These tests examine stool samples to look for signs of colon cancer. Examples include guaiac-based fecal occult blood test (gFOBT) and stool DNA test. You can do these tests with home kits. However, they mainly screen for cancer that has already developed and aren’t reliable for detecting polyps. As a result, you need these tests every year. If a test comes back positive, you will need a colonoscopy. Stool collected during a DRE (digital rectal exam) is only a single sample and not adequate for colon cancer screening.

Other exams, such as a sigmoidoscopy or double-contrast barium enema, are not common screening exams in the United States.

If your doctor finds a problem during a screening exam, you will need additional tests, such as blood tests for tumor markers and imaging exams for cancer staging. Diagnosing the type and stage of colon cancer helps determine your prognosis and treatment options. There are five main stages of colon cancer, and about 40% of colon cancers are in an early stage at diagnosis. These early stages are highly treatable and have high survival rates. Unfortunately, only half of people who should have screening get it. Talk with your doctor about colon cancer screening and scheduling.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Feb 25
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.

  1. About Colorectal Cancer. American Cancer Society.

  2. Cancer Staging. National Cancer Institute.

  3. Colon Cancer. National Cancer Institute.

  4. Colon Cancer Treatment. National Cancer Institute.

  5. Colorectal Cancer: Causes, Risk Factors, and Prevention. American Cancer Society.

  6. Colorectal Cancer: Early Detection, Diagnosis, and Staging. American Cancer Society.

  7. Obesity and Cancer. National Cancer Institute.