Routine colonoscopies can find colon cancer in its early stages. This screening procedure allows your doctor to carefully examine your colon for signs of polyps (abnormal growths on the inside surface of the colon).
Your treatment team may recommend one of the following colon cancer screening tests.
A colonoscopy is a test in which a thin, flexible tube with a light and a video camera on its tip is placed in your colon to search for polyps. It’s the most effective way to detect them. Your treatment team will prescribe a clear-liquid diet and medication to clear out your bowel during the 24 hours before the procedure. You’ll also be sedated during the exam. Your doctor can usually remove any polyps that are detected, which then go to a pathologist (a doctor who specializes in diagnosing disease) for examination and analysis.
A flexible sigmoidoscopy is similar to a colonoscopy. The main difference is that your doctor uses a shorter tube to examine the lower part of your colon.
A virtual colonoscopy (VC) — also known as a CT colonography — is an alterative option performed in some patients by a radiologist. This study uses CT scan technology to create 2-D and 3-D images of your large bowel. It does not require sedation. VC has limitations, however. For example, it requires the same preparation as conventional colonoscopy — a clear-liquid diet and medication to clear out your bowel. In addition, if the study detects a polyp or other abnormality in the colon, then you may need to undergo a colonoscopy for further management. VC can also sometimes miss small or flat polyps.
Fecal Occult Blood Test
Because colon or rectal bleeding can be a possible sign of colon cancer, a fecal (stool) occult blood test may detect small amounts of blood in your stool that are not otherwise visible. The test works like this: For three consecutive days, you’ll place small stool samples on chemically treated cards. You’ll send those cards to a lab for testing. During this time, you’ll have to follow a special diet to ensure accurate test results. If an abnormality is detected, you may need to undergo a colonoscopy for further management.
Fecal Immunochemical Test
A fecal immunochemical test (FIT) also screens for colon cancer by detecting blood in the stool. Unlike more traditional fecal occult blood testing, you don’t have to follow a special diet before the test. FIT reacts to a part of the hemoglobin molecule (a protein found in red blood cells). If an abnormality is detected, you may need to undergo a colonoscopy for further management. This test is also called immunochemical fecal occult blood test.
Stool DNA Test
A stool DNA test also screens for cancer by looking for gene changes and blood in your stool sample. Like FIT, you do not need to follow a specific diet prior to submitting a sample. And like the other stool tests, if an abnormality is detected, you may need to undergo a colonoscopy for further management.