Mayo Clinic Q&A: Screening Is an Important Step in Preventing Colon Cancer

Mayo Clinic Q&A: Screening Is an Important Step in Preventing Colon Cancer

DEAR MAYO CLINIC: Are there ways to prevent colon cancer? What about early symptoms to watch for? I just turned 50, and I’ve heard colon cancer is more common as you get older. I’d like to lower my risk of getting this disease as much as possible.

ANSWER: There are some lifestyle changes that may lower your risk of developing colon cancer. But one of the most important steps you can take at your age is getting the recommended colon cancer screening. Although early-stage colon cancer rarely causes symptoms, screening exams can detect the disease early — sometimes even before it’s become cancer — when it often can be treated effectively.

Colon cancer is common, affecting about one in 20 people. In most cases, symptoms, such as persistent abdominal pain, rectal bleeding or blood in the stool, don’t appear until the disease is in its advanced stages.

Age is one of the most significant risk factors for colon cancer. Most cases are diagnosed in people older than 50. Therefore, screening begins at 50 for people with an average risk of developing colon cancer. Some people with an increased risk, such as those with a family history of the disease, may need to start screening sooner.

Colonoscopy is the most common colon cancer screening test. During a colonoscopy, a long, flexible tube, called a colonoscope, is inserted into the rectum. A tiny video camera at the tip of the tube allows your healthcare provider to detect changes or abnormalities inside the entire colon.

Other screening tests are available, too. One is computerized tomography (CT) colonography — sometimes called a virtual colonoscopy. It uses CT imaging to produce a detailed view of the inside of the colon and rectum. It doesn’t require insertion of a scope into the colon.

Another alternative is the fecal immunochemical test. This lab test checks stool samples for microscopic amounts of blood shed from colon cancer that may not be visible to the human eye.

The newest screening option is the multitarget stool DNA test. This test looks for DNA molecules that colon cancer and polyps may shed into stool, in addition to hemoglobin. The test can be done from home and doesn’t require bowel preparation or medication restrictions.

If results from a stool DNA test, fecal immunochemical test or CT colonography are positive, a follow-up evaluation with a full colonoscopy is required.

The purpose of screening is to detect abnormalities within the colon, such as polyps or early-stage cancers. Not all colon polyps develop into cancer, but most colon cancers begin as polyps. Promptly detecting and removing polyps significantly reduces the risk of developing the disease.

The results of your initial screening exam determine how often you need follow-up screening. In addition to getting those tests as recommended, you can take steps in your daily life to lower your risk.

Excessive alcohol use, obesity, lack of exercise and smoking can raise the risk of colon cancer. Therefore, if you drink alcohol, do so only in moderation. That means no more than one drink a day for women and no more than two for men. Don’t smoke. If you do, talk to your healthcare provider about ways to quit.

If you are at a healthy weight, work to maintain your weight by combining a healthy diet with daily exercise. Try to get at least 30 minutes of exercise most days. If you need to lose weight, ask your healthcare provider about healthy ways to achieve your goal.

There are some risk factors you can’t control, such as family history and medical history. If you have questions about your risk of colon cancer, or you’re not sure which screening option is right for you, talk to your healthcare provider. — John Kisiel, MD, Gastroenterology, Mayo Clinic, Rochester, Minn.

(Mayo Clinic Q & A is an educational resource and doesn’t replace regular medical care. E-mail a question to MayoClinicQ& For more information, visit