Colon Cancer Screening Options
There are multiple screening options available, which can often be confusing for the patient. For anyone at high risk for colon cancer, colonoscopy is the only recommended strategy.
- Any screening test is better than no screening test! The best test for you is the one you will actually complete.
- Average risk individuals should start screening at age 50, and for African Americans at age 45.
- High-risk individuals need to begin screening before age 50 and should be screened more frequently.
- Persons with a family history of colon cancer should begin testing 10 years earlier than their relative's age at diagnosis.
Structural tests of the colon detect both polyps and cancers. The gold standard structural screening method is the colonoscopy.
Double Contrast Barium Enema
The patient is given an enema with barium followed by air. The air pushes the barium against the walls of the colon in order to better visualize potential problems, such as polyps and tumors.If the test is abnormal, a complete colon evaluation is necessary. View diagram.
Colonoscopy is the single most reliable test for detection of polyps and cancer.Your doctor will examine the inside of your colon and rectum using a long, lighted tube called a colonoscope.Your doctor will check for abnormalities such as polyps. Generally, if a polyp is found, it can be removed with the scope. Removal of polyps is essential in prevention of colon cancer.A colonoscopy should be performed every 10 years in a normal risk person. If polyps are found during a colonoscopy or if the person is moderate or high risk for colon cancer, a more frequent evaluation may be needed. View diagram.
The doctor will examine the rectum and only the lower portion of the colon with a lighted tube. If polyps are found, a complete colon exam, such as colonoscopy will be needed to further evaluate the possibility of other polyps in higher regions of your colon unable to be reached by sigmoidoscopy. View diagram.
Images of the colon and rectum are taken using computerized tomography (CT). A computer puts the images together to create an animated, three-dimensional view. If abnormalities are detected, a colonoscopy is necessary. View diagram.
Only a colonoscopy allows for both identification and removal of colon polyps throughout the entire colon and rectum. All others require bowel prep, and if positive, will require a colonoscopy for confirmation and polyp removal.
For average risk individuals, colonoscopy is recommended once every 10 years starting at age 50, and for African Americans at age 45 by several societies.
Higher levels of risk require more frequent testing intervals. If polyps (specifically a type of polyp called an adenoma) are found then follow up surveillance with colonoscopy is recommended every 5 years.Shorter or longer intervals are dependent on the number, size, and character of the polyps identified.
For more detailed screening information, see the Colorectal Cancer Screening Tip Sheet.
For any structural test, good bowel prep is essential to safely and accurately identify polyps. The goal of prep is to eliminate all fecal matter from the colon so that the physician conducting the exam will have a clear view. Your physician will instruct you to ingest a particular prep medication, often tablets or a powder to be dissolved in water. If you have significant heart, liver, or kidney problems, ask your physician whether you need specifically tailored preps. Drinking lots of fluids helps avoid dehydration. All preparations will result in multiple bowel movements, so set aside the evening before your exam in a comfortable convenient location (near the bathroom).
If colonoscopy is not for you, then you do have options.
Stool analysis requires a sample (or samples) of stool to test for evidence of bleeding or genetic abnormalities associated with colon cancer or large polyps. These tests are not designed to detect small or medium sized polyps in their earliest stages. In order for these to effectively reduce colon cancer death rates they must be repeated on an annual basis.The sensitivity and accuracy of these tests continue to improve. When followed carefully, stools testing allows for intervention and detection of colon cancer at early stages leading to higher survival rates.
Fecal Occult Blood (FOB) Testing
Fecal Occult Blood testing should begin at the age of 40 and occur yearly as a part of a physical examination. FOB tests stool for the presence of blood, an indication of presence of polyps (growths found within the colon that can over time develop into cancer). A positive FOB test requires a complete colon examination, such as colonoscopy.