Colon Cancer: Who Is at Risk, and How Can It Be Prevented?

Colon Cancer, Prevention
Noy Birger, Brandel France de Bravo, MPH, Alea Sabry, and Melissa Stoner,  Cancer Prevention & Treatment Fund

When cancer begins in the colon (large intestine) or rectum, it is called colorectal cancer or colon cancer.

 

In the early stages, this cancer begins with small polyps, which are shaped like little mushrooms growing on the wall of the colon. Polyps are very common, especially as people get older. Not all polyps develop into cancer, but all colorectal cancer begins with polyps. Certain kinds of polyps are more likely to lead to cancer than others, but the doctor can’t tell if a polyp is precancerous just by looking at it. This is why doctors prefer to remove and analyze any polyps found during screening. Polyps can be identified and removed by colonoscopy, in which a small camera on a flexible tube is inserted into the rectum.[1]

 

Despite the number of people diagnosed with colon cancer decreasing in recent years, it is still the third most common cancer for both men and women.[2][4] In recent years, there has been concern about the number of younger adults getting diagnosed, including some in their 20’s or 30’s. For people diagnosed at any age, the death rate can be reduced by the early detection of disease and by timely and appropriate treatment. Overall screening rates have increased for adults aged 50-75, but could be higher. Experts recently recommended lowering screening ages to start at 45, but screening for adults aged 45-49 remains low. [3][4]

 

A study published in February 2012 in New England Journal of Medicine found that patients who received colonoscopies and had noncancerous or pre-cancerous growths (polyps) removed, were half as likely to die from colon cancer than people in the general population who were not screened or used less effective screening methods. [5]

 

Men and women are equally likely to die from colon cancer, but men are more likely to be diagnosed with colon cancer than women of the same age.[6][7]. Non-Hispanic American Indian and Alaska Native men and women are at a higher risk for developing colorectal cancer. Black men and Black women continue to have a higher risk of dying from colorectal cancer compared to white men and white women of the same age.[8][9][10] Being overweight or obese increases men’s risk of colon cancer more than it does women’s (see Weight and Cancer: What You Should Know).

 

Risk Factors for Developing Colon Cancer

In addition to your sex and race, your age and genes are important risk factors you can’t do anything about. Your chances of developing colon cancer increase as you get older: 80% of cases are in people 55 and over.[10] Having a family member be diagnosed with colon cancer also slightly increases your chances of developing it, especially if they developed colorectal cancer at an earlier age. [11]

 

In addition to people with pre-cancerous polyps, people who suffer from ulcerative colitis or Crohn’s disease are more likely to develop colon cancer.[12] Ulcerative colitis and Crohn’s disease cause inflammation of the colon, which is why they are both also referred to as Inflammatory Bowel Disease (IBD). Chronic inflammation in the body seems to increase the risk of various types of cancer.

 

Less is known about what you can do to prevent colon cancer. People who eat too much fat in their diet or too little fiber or too little calcium, smoke, drink alcohol, don’t exercise enough, or are overweight are more likely to be diagnosed with colon cancer. However, scientists do not know whether people can lower their risks of getting colon cancer if they change one or more of those behaviors. Several recent meta analyses suggest that high-fiber diets can help prevent colorectal cancer. [13][14][15] Of course, there is very clear evidence that calcium, exercising, maintaining a healthy weight, and avoiding smoking and alcohol is generally good for your health, whether it reduces your chances of colorectal cancer or not.   

So, What Can You Do to Lower Your Risk?
  • Get screened regularly from age 45 to 75.[16] If you have a relative with colon cancer, your doctor may want to screen you earlier than age 40. The recommended screening tests are:
  • High Sensitivity Fecal Occult Blood Test (FOBT), which involves providing stool samples and should be done once every year
  • Colonoscopy (mentioned above) requires emptying out your colon using powerful laxatives that require being near a toilet for many hours. Most people consider this the worst part of a colonoscopy, although it is also an invasive procedure requiring anesthesia. If polyps are found, the doctor can remove them during the procedure. It is only needed every 10 years, or every 5 years if a close relative developed colon cancer.
  • Flexible sigmoidoscopy is similar to a colonoscopy. It can be used to find polyps but not to remove them. It is recommended every 5 years
  • Cologuard — A non-invasive multitarget stool DNA test designed to detect DNA mutations and methylations that can show the presence of cancer. However, its low specificity causes false-positive results, resulting in many unnecessary colonoscopies.[17]
  • CT Colonography (virtual colonoscopy) is less invasive than a traditional colonoscopy because it uses x-ray images of your colon and rectum. However, the preparation for a virtual colonoscopy is like that of a traditional colonoscopy, which involves the powerful laxatives described above. If abnormal growths or polyps are detected during a virtual colonoscopy, the patient will need to undergo a standard colonoscopy to remove them. Sometimes a virtual colonoscopy scan will find abnormalities outside of your colon. Additional screenings and expenses may be necessary to determine if those abnormalities are a potential health issue. [18] [19] As with any CT scan, a virtual colonoscopy exposes you to relatively high levels of radiation (see Everything You Ever Wanted to Know about Radiation and cancer, But Were Afraid to Ask).

 

Each screening method has pros and cons. A regular colonoscopy (not a virtual one) has the advantage of allowing doctors to remove polyps right away during the screening procedure. The downside of both types of colonoscopy is that you need to take a day off from work, fast for about 12 hours, and purge with large quantities of an unpleasant laxative drink or pills taken with lots of liquid. The Fecal Occult Blood Test is easier and less expensive, and like the CT colonography scan, it can detect potential problems or polyps. But, if anything unusual is found, you would still need a colonoscopy to have polyps removed. [20]

  • Quit smoking. Cigarette smoking doubles your chances of getting polyps and long-term smoking increases the risk of colon cancer. It also increases your chances of dying from colon cancer.[21][22][23]
  • Maintain a healthy weight. Extra pounds mean extra risk for all kinds of cancer, including colorectal cancer. Fat cells appear to trigger chronic inflammation of the body, which stresses the immune system.[24]
  • Do more physical exercise. Research suggests that moderate physical activity, like walking, gardening, or swimming, can help lower your risk of some cancers, including colorectal cancer. [25] [26] [27]. Current guidelines state that adults who want to stay healthy should be getting at least 150 minutes of moderate-intensity aerobic physical activity a week. [27] 
  • Eat a balanced diet. Be sure to include plenty of fruits and vegetables (especially ones from the cabbage family, like broccoli, cauliflower, cabbage, Brussels sprouts, and collard greens), and limit the amount of red meat you eat (particularly well-done). This strategy may lower your chances of developing cancer, and it definitely can help people live longer. So, why not try it? [28][29]
  • Fiber in your diet. High fiber diets can also reduce your likelihood of getting colorectal cancer. Fiber in your diet helps protect your colon by interfering with the processes that start cancer, balancing the gut microbiome, and providing a good source of antioxidants. [30][31]
  • Get more Vitamin D. While the U.S. Preventive Services Task Force doesn’t currently recommend the use of multivitamin supplements to prevent cancer, some studies suggest that low vitamin D levels may increase the chances of developing colorectal cancer, especially for women. [32] Since vitamin D has many health benefits (see more here), you should discuss vitamin D levels with your doctor if you are concerned about colon cancer, and especially if you are likely to have inadequate vitamin D.[33] This can include older individuals, people with dark skin, and those with limited access to sunlight [25].
  • Low-dose aspirin. Experts no longer recommend the use of low-dose aspirin to prevent colorectal cancer. Whether taking low-dose aspirin could help you to prevent cardiovascular disease depends on your medical history and should be discussed with your doctor. [34]
  • Avoid taking unnecessary antibiotics. Overusing antibiotics may increase your chances of colorectal cancer by disrupting the balance of healthy gut bacteria, but more research is needed to study the long-term effects of antibiotics on gut health.[35] Only take antibiotics when your physician agrees that it is necessary.

All articles on our website are reviewed and approved by Dr. Diana Zuckerman and other senior staff.

 

References:

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  34. Vitamin, mineral, and multivitamin supplementation to prevent cardiovascular disease and cancer: Preventive medication. Published June 21, 2022. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/vitamin-supplementation-to-prevent-cvd-and-cancer-preventive-medication
  35. Bassett, M. Are Antibiotics Linked to Early-Onset Colorectal Cancer?. Medpage Today. July 2021. https://www.medpagetoday.com/meetingcoverage/additionalmeetings/93412?xid=nl_mpt_DHE_2021-07-05&eun=g1146420d0r&utm_source=Sailthru&utm_medium=email&utm_campaign=Daily%20Headlines%20Top%20Cat%20HeC%20%202021-07-05&utm_term=NL_Daily_DHE_dual-gmail-definition