Colorectal cancer: The best screening test is the one you take

The University of Kentucky Public Relations and Strategic Communications Office provides a weekly health column available for use and reprint by news media. This week's column is by Avinash Bhakta, M.D., a colorectal surgeon at the University of Kentucky Markey Cancer Center.

LEXINGTON, Ky. (March 6, 2023) — Colorectal cancer is one of the leading causes of cancer-related deaths in Kentucky, and it often doesn’t cause symptoms, especially in its early stages. Regular screening, beginning at age 45, is the key to preventing this disease and finding it early.

There are two primary types of screening tests: visual exams, which include colonoscopies, and stool-based tests. While colonoscopy is the gold standard for screening, it is an invasive procedure that must be done in a clinic or hospital under sedation. Stool-based tests offer an alternative that is less invasive and can be more accessible.

Visual exams:

• Colonoscopies are extremely effective at detecting colorectal cancer and precancerous lesions. During this test, doctors will examine the rectum and entire colon using a colonoscope, and they can actually remove any abnormal growths as they find them. This screening requires a complete cleansing (“prep”) of the colon using an oral laxative.
• CT colonography: Also known as a virtual colonoscopy, this is a CT scan of the entire colon and rectum. It requires bowel prep, but patients do not need sedation. It is less invasive than a colonoscopy, but is diagnostic only — if polyps are found, patients will need a traditional colonoscopy to remove them.
• Sigmoidoscopy: This is very similar to a colonoscopy, but only looks at part of the colon. Most patients do not need sedation, and bowel prep is less extensive than a colonoscopy (two enemas only). If there is an abnormal finding, a full colonoscopy is required.

Stool-based tests: Stool-based tests check for blood and/or abnormal DNA in the stool, and can be done in the privacy of your own home. Patients collect their own samples using a kit that they return to their doctor or mail to a laboratory for testing. These tests include fecal occult blood tests (known as gFOBT or FIT tests) and stool DNA tests (Cologuard). Depending on the type of test you are given, there may be dietary restrictions prior to testing. All at-home tests need to be repeated on a yearly basis, and any positive findings will require a follow-up colonoscopy.

If work, transportation or family obligations are preventing you from getting a colonoscopy, you may want to consider a stool-based test. Speak with your doctor and insurance company to determine what test works best for you.

Regardless of which test you choose, the most important thing you can do is get screened.