Colon cancer screening tests
Colorectal screening tests help your doctor find cancer early, when it’s easier to treat and before symptoms show up. While diagnostic tests are used when a patient is showing symptoms and needs a diagnosis, screening tests are intended for healthy patients without symptoms.
A colonoscopy is the most comprehensive test for colon cancer screening. It takes about 30 to 60 minutes. It’s usually repeated every 10 years if no abnormalities are found, and you don’t have an increased risk of colon cancer. Abnormal polyps are removed during the exam. The procedure is done in an outpatient hospital setting and requires preparation.
To prepare for your colonoscopy:
- Don’t eat solid food the day before the test.
- Adjust any medications you’re taking, if necessary.
- Completely empty your intestines and bowels before the test.
Before your screening, your provider will give you detailed instructions for how and when to begin your colonoscopy preparation.
What happens during a colonoscopy?
During a colonoscopy, you’ll receive anesthesia to keep you relaxed and pain-free. While you lie on a table, the doctor will insert a small camera (colonoscope) through your anus into your rectum and colon. The camera allows the doctor to examine your large intestine for abnormalities like polyps and to take tissue samples if needed.
Polyps are common and usually harmless, but because colon cancer often starts as a polyp, your doctor may remove them to prevent cancer.
After the procedure, you will be monitored in a recovery area as you wake up from anesthesia. You might feel some cramping or bloating for a few hours.
Your care team will provide aftercare instructions. You won’t be able to drive, so plan for a friend or family member to take you home. Most people can return to normal activities the next day.
A virtual colonoscopy uses a CT scan to create cross-section images of the abdominal organs, helping to find changes or abnormalities in the colon. It takes about 10 minutes and is typically performed every five years.
This procedure doesn’t need sedation or a scope inside the colon. However, it does require complete bowel cleaning, as well as diet and medication adjustments beforehand. Since tissue samples cannot be taken during a virtual colonoscopy, a follow-up colonoscopy may be needed.
Stool DNA tests, like Cologuard, use a stool sample to look for DNA changes that might indicate colon cancer or precancerous conditions. You collect a stool sample at home and send it to a lab for testing. This test is usually done every three years.
However, this test is less sensitive than a colonoscopy at detecting precancerous polyps, so if abnormalities are found, additional tests may be needed.
Fecal occult blood test and fecal immunochemical test are lab tests that look for hidden (occult) blood in your stool and are repeated every year.
These tests may not detect some polyps and cancers. Before the tests, certain foods and medications might need to be avoided for several days. If occult blood is detected, further tests may be needed.
Fecal occult blood test and fecal immunochemical test are lab tests that look for hidden (occult) blood in your stool and are repeated every year.
These tests may not detect some polyps and cancers. Before the tests, certain foods and medications might need to be avoided for several days. If occult blood is detected, further tests may be needed.
High-sensitivity guaiac fecal occult blood test (gFOBT)
High-sensitivity guaiac fecal occult blood test uses a chemical substance called guaiac to check for blood in three consecutive stool samples. The small samples of stool, which are collected at home, are placed on a special card and returned to a doctor or laboratory for testing. If used, this test is recommended to be done annually.
Flexible sigmoidoscopy is an exam that’s used to evaluate the lower part of the colon using a flexible tube with a tiny video camera at the tip. If necessary, the doctor may also perform a biopsy during this procedure. This exam is recommended every five years.