Screening

Screening for colon cancer should be a part of routine care for all adults aged 50 years and older or patients who are <50 and symptomatic, especially for those with first-degree relatives with colorectal cancer. This recommendation is based on the frequency of the disease, ability to identify high-risk groups, slow growth of primary lesions, better survival of patients with early-stage lesions, and relative simplicity and accuracy of screening tests. For more information, see Colorectal Cancer Screening.

Carcinoembryonic Antigen (CEA) assay is a test that measures the level of CEA in the blood. CEA is released into the bloodstream from both cancer cells and normal cells. When elevated, it can be a sign of colon cancer or other conditions. See Biomarkers (tumor markers) for more information on CEA.

Fecal Occult Blood Test (FOBT) is a test to check stool (solid waste) for blood that can only be seen with a microscope. A small sample of stool is placed on a special card or in a special container and returned to the doctor or laboratory for testing. Blood in the stool may be a sign of polyps (small pieces of bulging tissue), cancer, or other conditions.

There are two types of FOBTs

• Guaiac FOBT: The sample of stool on the special card is tested with a chemical. If there is blood in the stool, the special card changes color.
• Immunochemical FOBT: A liquid is added to the stool sample. This mixture is injected into a machine that contains antibodies that can detect blood in the stool. If there is blood in the stool, a line appears in a window in the machine. This test is also called fecal immunochemical test or FIT.

Updated: June 24, 2025