Understanding your colon cancer risk
Colon cancer - prevention; Colon cancer - screening
Colorectal cancer risk factors are things that increase the chance that you could get colorectal cancer. Some risk factors you can control, such as drinking alcohol, diet, and being overweight. Others, such as family history, you cannot control.
The more risk factors you have, the more your risk increases. But it does not mean you will get cancer. Many people with risk factors never get cancer. Other people get colorectal cancer but do not have any known risk factors.
Learn about your risk and what steps you can take to prevent colorectal cancer.
Colon cancer may not be talked about as often as other cancers, like breast cancer, prostate or lung cancer, but it's actually one of the leading causes of cancer deaths. It is for this reason it's very important to stay on top of your colon health. The colon is your large intestine, the long, upside-down U-shaped tube that is toward the end of the line for getting rid of waste in your body. Colon cancer can start in the lining of the intestine, or at the end of it, called the rectum. Let's try to better understand Colon cancer. You're more likely to get the disease if you're over age 60, especially if you have a family history of colon cancer, inflammatory bowel disease, diabetes, or obesity. Smoking cigarettes and drinking alcohol has also been found to increase your risk of getting colon cancer. Although the data are not consistent, eating red meat or processed meats may increase the risks of colon cancer as well. Lean, unprocessed red meat, may be associated with less risk. If you have symptoms, they may include pain in your abdomen, blood in your stool, weight loss, or diarrhea. But hopefully, you'll get diagnosed before you have any symptoms, during a regular screening test like a colonoscopy or sigmoidoscopy. These tests use special instruments to see inside your colon and rectum to look for any cancerous or pre-cancerous growths, called polyps. If your doctor discovers that you do have colon cancer, unfortunately, you'll need to have a few more tests, including scans of your abdomen to find out whether the cancer has spread, and if so, where in your body it's located. So, how is colon cancer treated? That really depends on how aggressive your cancer is and how far it's spread, but usually colon cancer is removed with surgery, or killed with chemotherapy or radiation. You may get one, or a combination, of these treatments. Colon cancer is one of the more treatable cancers. You can be cured, especially if you catch it early. Spotting colon cancer when it's still treatable is up to you. If you're over age 45, you need to get screened. And, regular physical activity and eating at least some fruits and vegetables daily, perhaps with unprocessed wheat bran, can help prevent it. If you want to prevent colon cancer, you'll also want to avoid processed and charred red meats, and smoking, and excess calories, and alcohol.
We do not know what causes colorectal cancer, but we do know some of the things that may increase the risk of getting it, such as:
- Your risk increases after age 45
- You have had colon polyps or colorectal cancer
- You have inflammatory bowel disease (IBD), such as ulcerative colitis or Crohn disease
- Family history of colorectal cancer or polyps in parents, grandparents, siblings, or children
- Gene changes (mutations) in certain genes (rare)
- African American or Ashkenazi Jews (people of Eastern European Jewish descent)
- Type 2 diabetes
- Diet high in red and processed meats
- Physical inactivity
- Heavy alcohol use
How to Reduce Your Risk
Some risk factors are in your control, and some are not. Many of the risk factors above, such as age and family history, can't be changed. But just because you have risk factors you can't control doesn't mean you can't take steps to lower your risk.
Start by getting colorectal cancer screenings at age 45. You may want to start screening earlier if you have a family history of colorectal cancer. Screening can help prevent colorectal cancer, and it is one of the best things you can do to lower your risk.
Certain lifestyle habits also may help lower your risk:
- Maintain a healthy weight
- Eat a low-fat foods with plenty of vegetables and fruits
- Limit red meat and processed meat
- Get regular exercise
- Limit alcohol to no more than 1 drink per day for women and 2 drinks per day for men
- Do not smoke
- Supplement with vitamin D (talk to your health care provider first)
You can also have genetic testing done to assess your risk for colorectal cancer. If you have a strong family history of the disease, talk with your provider about testing.
Low-dose aspirin may be recommended for some people who are at very high risk for colorectal cancer found with genetic testing. It is not recommended for most people because of side effects.
Colon cancer is one of the leading causes of cancer-related deaths in the United States. The good news is that earlier diagnosis due to screening tests often leads to a complete cure. Colorectal cancer starts in the large intestine, also known as the colon. Nearly all colon cancers begin as noncancerous, or benign, polyps, some of which may slowly develop into cancer. Screening can detect these polyps and early cancers. Polyps can be removed years before cancer even has a chance to develop. Your doctor can use two types of tools to screen for cancer. The first type is a stool test. Polyps in the colon and small cancers can bleed tiny amounts of blood that you can't see with the naked eye. The most common method to test for the presence of blood is the fecal occult blood test or FOBT. This test checks your stool for small amounts of blood that you may not be able to see. Two other stool tests are the fecal immunochemical test and the stool DNA test. The second type of screening tests involve looking at the lining of the colon. One of these tests is a sigmoidoscopy exam. This test uses a flexible scope to look at the lower portion of your colon. But, because it looks only at the last one-third of the large intestine, it may miss some cancers. So this test is done along with a stool test. A colonoscopy is similar to sigmoidoscopy, but it can see the entire colon. For this test, your doctor will give you instructions for cleansing your bowel. This is called bowel preparation. During the colonoscopy, you’ll receive medicine to make you relaxed and sleepy. Another test your doctor may recommend is a virtual colonoscopy, also called a CT colonography. This test uses a CAT scan and computer software to create a 3-D image of your large intestine. Beginning at age 45, all men and women should have a screening test for colon cancer. Screening options for people with average risk for colon cancer include visual based exams. These could be a colonoscopy every 10 years starting at age 45 or a virtual colonoscopy every 5 years. A Flexible sigmoidoscopy every 5 years or a Flexible sigmoidoscopy every 10 years plus stool testing with FIT done every year. Screening options also include stool based tests. People with average risk should have an FOBT or FIT every year. A colonoscopy is needed if the results are positive, or a Stool DNA test every 1 to 3 years. A colonoscopy is needed if the results are positive. People with certain risk factors for colon cancer may need screening at a younger age, or they may need screening more often. Such people include those with a family history of colon cancer, those with a history of previous colon cancer or polyps, or people with a history of ulcerative colitis or Crohn disease. The death rate for colon cancer has dropped in the past 15 years and this may be due to increased awareness and colon screening. In general, early diagnosis is much more likely to lead to a complete cure.
When to Call the Doctor
Call your provider if you:
- Have questions or concerns about your colorectal cancer risk
- Are interested in genetic testing for colorectal cancer risk
- Are due for a screening test
Itzkowitz SH, Potack J. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 126.
Lawler M, Johnston B, Van Schaeybroeck S, et al. Colorectal cancer. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 74.
National Cancer Institute website. Colorectal cancer prevention (PDQ) - health professional version.
US Preventive Services Task Force website. Final recommendation statement. Colorectal cancer screening.
Last reviewed on: 7/17/2020
Reviewed by: Michael M. Phillips, MD, Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 08/02/2021.