No. Stool-based tests, CT colonography, and flexible sigmoidoscopy are also used for colon cancer screening, although an abnormal result on any of them usually leads to a colonoscopy. The right choice depends on your risk level, how you feel about bowel prep and sedation, and how often you’re willing to repeat a test. Center for Colorectal Disease of Arizona, a colon and rectal practice serving Surprise and nearby West Valley communities, suggests asking about alternative screening methods when a scope exam is first recommended, so the decision is made with the trade-offs in view.
That conversation is easier when you know what each option involves. The comparison below draws on guidance from the National Cancer Institute (NCI) and the U.S. Preventive Services Task Force (USPSTF), which recommends that adults at average risk start screening at age 45.
Why Do Several Screening Tests Exist?
Screening looks for cancer before symptoms begin, when it’s generally easier to treat. Some tests can also find and remove precancerous growths called polyps, which may prevent cancer from developing at all. Other tests are simpler and less invasive but can only flag that something needs a closer look.
NCI notes that more invasive tests carry more potential for harm, while less invasive tests need to be repeated more often and may lead to follow-up procedures. No single test is best for everyone. The best test is generally one you’ll actually complete, and repeat on schedule.
That matters in Arizona. According to the Arizona Department of Health Services, about 58% of colorectal cancers diagnosed in the state from 2017 to 2021 were found at a late stage, which is the problem regular screening is meant to prevent.
How Do the Main Screening Tests Compare?
Stool tests you do at home
The fecal immunochemical test (FIT) uses antibodies to detect hidden blood in stool and typically needs no diet changes. The guaiac-based test (gFOBT) detects blood chemically, and NCI notes that people may need to avoid certain foods, such as red meat, beforehand. Used alone, both are generally repeated every year or two.
The stool DNA test combines a check for hidden blood with a check for DNA changes shed from the colon lining. NCI lists an interval of at least every three years. All of these tests are done with a home kit, with no bowel prep or sedation. The trade-off is that a positive result needs a follow-up scope exam to find the cause.
Flexible sigmoidoscopy
This exam uses a scope to look at the rectum and the lower part of the colon only. Prep is less extensive and sedation usually isn’t needed. Growths in that section can be removed or biopsied, but the rest of the colon isn’t examined, and NCI notes the test isn’t widely available in the U.S.
CT colonography
Sometimes called virtual colonoscopy, this test uses a CT scanner to create images of the colon. It still requires bowel cleansing but no sedation, and NCI lists an interval of every five years. It may miss small polyps, involves some radiation, and can turn up findings outside the colon that need their own follow-up. If polyps are seen, a standard scope exam is usually needed to remove them.
Colonoscopy
A flexible, lighted scope examines the entire colon and rectum, and abnormal growths can often be removed during the same exam. It requires the most thorough bowel prep, and most people are sedated, so you’ll need a ride home. For people at average risk with normal results, NCI lists an interval of every 10 years. There is a small risk of a tear or perforation in the colon lining.
What about blood tests and in-office stool checks?
NCI notes that some blood-based screening tests have FDA approval but aren’t yet part of clinical guidelines for first-line screening. It also notes that a single stool sample taken during a rectal exam in the doctor’s office isn’t an effective way to screen. If either is offered to you as a screening option, ask how it compares with the tests above and what would happen if the result were abnormal.
What Happens If a Different Test Comes Back Abnormal?
An abnormal stool test, sigmoidoscopy, or CT colonography result isn’t a diagnosis, but it does mean screening isn’t finished. The usual next step is a follow-up scope exam to examine the whole colon and find the cause.
That follow-up exam is where polyps can be removed and tissue samples taken. If cancer is found, the next steps depend on what the exam and lab results show, and treatment can include colorectal cancer surgery along with other options a specialist will discuss. Because the follow-up is part of the screening process, it’s worth deciding before you choose a home test whether you’d be willing and able to complete one.
When Is a Full Scope Exam Usually the Better Fit?
The USPSTF options are designed for adults at average risk. NCI notes that some people may be advised to start screening earlier, be screened more often, or both, including people with:
- Inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease
- A family history of colorectal cancer
- Inherited conditions such as Lynch syndrome or familial adenomatous polyposis
- A personal history of advanced polyps
If you’re receiving Crohn’s disease treatment, your screening plan may look different from the standard schedule, so ask the clinician managing your condition which test and timing apply to you.
A scope exam can also make sense for people who would rather handle prep and sedation once every several years than repeat a home test every one to three years, or who want any polyps found and removed in the same visit. Those are personal preferences, and they’re worth stating plainly when you discuss options.
What If You Already Have Symptoms?
Screening is meant for people without symptoms. If you have rectal bleeding, a change in bowel habits, abdominal pain, or unexplained weight loss, that isn’t a screening question. The National Institute of Diabetes and Digestive and Kidney Diseases lists these among the symptoms doctors may investigate with a scope exam, and choosing a home screening kit instead may delay the right evaluation.
Hemorrhoids can cause visible bleeding, and NCI notes they can also cause hidden blood that shows up on a stool test. Still, don’t assume bleeding is “just hemorrhoids,” even if you’ve had hemorrhoids treatment before. New or changing bleeding can have more than one cause and should be checked by a clinician.
How Do Cost and Logistics Factor In?
Most private health plans, including Marketplace plans, must cover recommended colorectal cancer screening as a preventive service, and Medicare Part B covers several screening tests for eligible people, including stool tests, colonoscopy, and CT colonography. The details still vary, so check before you choose. Under current federal rules, Medicare and most private plans treat a colonoscopy after a positive stool test as part of screening rather than a separate diagnostic exam, though some plans, such as grandfathered plans, may not follow these rules. With Medicare, you may owe coinsurance if a polyp is removed during the colonoscopy. Medicare covers CT colonography when a clinician orders it and age and frequency limits are met, while coverage from other insurers varies. Your plan can confirm what you would owe for both the screening test and any follow-up.
Logistics count too. A scope exam means a day of prep, a ride home, and time for recovery, and it may take place at a hospital, an outpatient center, or a GI clinic depending on who performs it. A home stool test avoids all of that but needs to be repeated more often. Neither option is better in the abstract; the better one is the one that fits your health, your coverage, and your schedule.
Questions to Bring to Your Screening Conversation
NCI suggests asking practical questions before any screening test. For colon cancer screening, these are worth raising:
- Based on my risk, which screening tests are appropriate for me?
- How often would I need to repeat each test?
- What preparation does each test require, and what are its risks?
- If a home test is positive, how soon would I need a follow-up exam?
- How does my insurance cover the screening test and any follow-up?
- How and when will I get my results, and whom do I call if I don’t?
Writing down your answers makes it easier to compare options side by side, especially if you’re deciding between a home test and a scope exam for the first time.
About Center for Colorectal Disease of Arizona
Center for Colorectal Disease of Arizona provides colon and rectal care from offices in Surprise, Peoria, and Avondale, including colorectal cancer screening, treatment of hemorrhoids, and care for inflammatory bowel disease. Their surgeons are board-certified general surgeons with fellowship training in colon and rectal surgery. Their Surprise/Sun City West office is at 18715 N Reems Rd, Suite 140, and the practice can be reached at (623) 440-6591. For hours and directions, view their Google Business Profile.