Veteran's Health Library Menu

Health Encyclopedia

Colorectal Cancer Screening

Colorectal cancer (cancer in the colon or rectum) is a leading cause of cancer deaths in the U.S. But it doesn’t have to be. When this cancer is found and removed early, the chances of a full recovery are very good. Colorectal cancer rarely causes symptoms in its early stages, so screening for the disease is important. It’s even more important if you have risk factors for the disease. Learn more about colorectal cancer and its risk factors. Then talk with your healthcare provider about being screened. 

Risk Factors for Colorectal Cancer

Your risk of having colorectal cancer increases if you:

  • Are age 50 or older

  • Have a family history or personal history of colorectal cancer or adenomatous polyps

  • Have a personal history of certain kinds of colorectal polyps, Crohn’s disease, or ulcerative colitis

  • Have a family history of colorectal cancers

The Colon and Rectum

Waste from food you eat enters the colon from the small intestine. As it travels through the colon, the waste or stool loses water and becomes more solid. Intestinal muscles push it toward the sigmoid—the last section of the colon. Stool then moves into the rectum, where it’s stored until it’s ready to leave the body during a bowel movement.

How Cancer Develops

Front view cross section of sigmoid colon, rectum and anus.

Polyps are growths that form on the lining of the colon or rectum. Most are benign, which means they aren’t cancerous. But in a small number of people, polyps can become cancerous (malignant). This happens when cells in these polyps begin growing abnormally. In time, malignant cells invade more and more of the colon and rectum. The cancer may also spread to nearby organs or lymph nodes or to other parts of the body. Finding and removing polyps can help prevent cancer from ever forming.

Your Screening

Screening means looking for a medical problem before you have symptoms. During this time, treatment works better. During screening for colorectal cancer, your healthcare provider will ask about your medical history, discuss the options with you, and recommend one or more tests.

History and Exam

Your healthcare provider will ask about your medical history. Mention if a family member has had colon cancer or polyps. Also talk about any health problems you have had in the past.

Possible Tests and Exams

Image of colon with scope inside during a colonoscopy.

Image of colon with scope inside during a sigmoidoscopy.

There are several tests and exams that check you for signs of cancer. They include:

  • Fecal Occult Blood Test. This checks for blood in stool that you can’t see. Hidden blood may be a sign of colon polyps or cancer. A small sample of stool is tested for blood in a laboratory. Most often, you collect this sample at home using a kit your healthcare provider gives you. Follow the instructions carefully for using this kit. One kind of stool test requires you to avoid certain foods and medicines before the test. It is not necessary for another kind of stool test. Check with your healthcare team for directions. If blood is found in your stool, a colonoscopy is usually recommended to look for polyps or cancer.

  • Virtual colonoscopy. This test is only recommended for special situations. It uses a series of X-rays to create a 3-D view of the colon. During the test, you will lie on a table that is part of a special X-ray machine. A small tube will be inserted into your rectum. Then, the table will move into the machine and photos will be taken of your colon. A computer will combine these photos to create a 3-D picture. You still might need a colonoscopy if the test shows something abnormal.

  • Scope Exams. Scope exams include the following:

    • Colonoscopy. The day before the test, you will take laxatives to cleanse your colon. You will be given instructions for this. Just before the test, you are given a medicine to make you sleepy. Then, a long, flexible, lighted tube called a colonoscope is gently inserted into the rectum. It is guided through the entire colon. Images of the colon are viewed on a video screen. If polyps are found, they can usually be removed at that time and sent to a lab for testing. If a polyp can’t be removed, a sample of tissue is taken and the polyp is removed later during surgery.

    • Sigmoidoscopy. This test is similar to colonoscopy, but focuses only on the sigmoid colon and rectum. As with colonoscopy, bowel prep must be done the day before this test. This is usually done with enemas. You are awake during the test. During the test, the healthcare provider guides a thin, flexible, lighted tube called a sigmoidoscope through your rectum and lower colon. The images are displayed on a video screen. If polyps are found, they may be removed and sent to a lab for testing. You still might need a colonoscopy, depending on the type of polyp.

Author: StayWell Custom Communications
Last Annual Review Date: 2/1/2018
Copyright © The StayWell Company, LLC. except where otherwise noted.
Disclaimer - Opens 'Disclaimer' in Dialog Window | Help | About Veterans Health Library