Colon Cancer Screening: Tests, Ages, and What to Expect

Colorectal cancer remains the third most common cancer and second leading cause of cancer death in the United States, according to the American Cancer Society (ACS).

The ACS estimates that 158,850 new cases of the disease were diagnosed in the U.S. in 2026, with 55,230 deaths.

What Is Colon Cancer Screening?

Yet, many of these cases and deaths could be avoided with colorectal cancer screening. Colorectal cancer is one of the most preventable cancers because screening can identify and remove precancerous colorectal polyps before they become cancer.

Today, people have more colon cancer screening choices than ever, including newer stool- and blood-based tests outlined in an ACS guideline update (CA: A Cancer Journal for Clinicians, May/June 2026). No matter which screening approach you choose, the most important thing is to undergo colorectal cancer screening. So, review all your options with your doctor, weigh the pros and cons of each, and make an educated decision about which is best for you.

“Not all screening methods are equal in terms of precancerous lesions and detection of early-stage cancer,” says Carole Macaron, MD, a Cleveland Clinic colorectal cancer specialist. “So, the nuance is very important, and sharing that information with a patient is key to helping them make an informed and appropriate decision.”

When Should You Start Colon Cancer Screening?

Advancing age is one of the key colorectal cancer risk factors. Earlier guidelines recommended that adults at average risk of colorectal cancer begin screening at age 50. However, in 2018, the ACS lowered this recommended screening age to 45 in response to data showing rising rates of colorectal cancer in younger individuals.

The ACS notes that people at increased colorectal cancer risk should begin screening at a younger age. Higher-risk individuals include those with inflammatory bowel disease, a family history of colorectal cancer, a personal history of colorectal cancer or precancerous polyps, a genetic syndrome that increases colorectal cancer risk, or a history of abdominal or pelvic radiation for a previous cancer.

The ACS recommends continuing regular colon cancer screening through age 75 if you remain in good health. If you’re ages 76 to 85, discuss screening with your healthcare provider to determine if continuing it is appropriate based on your prior screening history and overall health and life expectancy. Screening is not recommended after age 85 or if your life expectancy is less than 10 years.

ACS Recommended Screening Intervals

*Not preferred
Source: “Colorectal cancer screening: An update to the American Cancer Society guideline, 2026.” CA: A Cancer Journal for Clinicians, May/June 2026

What Are the Main Colon Cancer Screening Tests?

Colorectal cancer screening tests fall into three categories: direct visual exams, stool-based tests, and blood-based tests. The ACS guidelines recommend that people eligible for screening be offered a choice between direct visual exams and stool-based testing.

Direct Visual Exams

• Colonoscopy. Widely considered the “gold standard” screening approach, colonoscopy is an endoscopic exam of the entire colon and rectum. It can also be used to remove any precancerous polyps during the exam. Of all the screening options, colonoscopy is the most sensitive for detecting these polyps, Dr. Macaron says, and it’s the only screening option recommended for people at high colorectal cancer risk.
• Flexible sigmoidoscopy (flex sig). This endoscopic exam of the rectum and lower third of the colon also allows for removal of precancerous lesions. Unlike colonoscopy, it doesn’t require an extensive bowel cleansing or sedation, so it may be preferable for individuals who need to return to work after the procedure. Dr. Macaron says she doesn’t typically order flex sig for her patients because it has been almost completely replaced by colonoscopy.
• CT colonography. In this noninvasive screening method, a physician uses sophisticated computed tomography (CT) imaging to visualize the entire colon and rectum. Also known as “virtual colonoscopy,” it requires a full bowel cleansing and inflation of the colon, but no sedation is necessary. Dr. Macaron says she reserves CT colonography for cases in which anatomical issues or other factors prevent her from completing a colonoscopy and examining the entire colon.

Stool-Based Tests

Stool-based tests are simple and convenient ways to screen for colorectal cancer because they require no bowel cleansing or sedation and can be done at home. Options include:

• Fecal immunochemical test (FIT). This test identifies hidden blood originating in the colon—an older test, the high‐sensitivity guaiac fecal occult blood test (FOBT), also identifies blood in the stool, but it cannot tell whether that blood originated in the colon or other parts of the digestive tract. The FIT test is 82% to 83% sensitive for detecting colorectal cancer and has a low rate of producing false-positive results, Dr. Macaron says. However, since the test looks for blood in the stool and not all polyps bleed (or they bleed intermittently), FIT detects only about a third of precancerous lesions, she adds.
• Multi-target stool DNA test (Cologuard). This screening combines FIT with testing for DNA changes in colon and rectal cells that may indicate colorectal cancer or polyps. The next-generation version of the test (Cologuard Plus) is about 95% effective at identifying colorectal cancer and 43% effective at detecting advanced precancerous polyps. Like the FIT test, it’s done at home, and the results are sent to a lab for analysis. One potential downside is that, whereas FIT entails scraping only a small stool sample with a stick or brush, the stool DNA test requires a larger sample and a more involved collection process, which can lead to test failure in about 3% to 6% of cases, Dr. Macaron says. She adds that she emphasizes to patients to read the instructions and make sure the sample is collected properly.
• Multi-target stool RNA test (ColoSense). The ACS guideline update added this test to the recommended colorectal cancer screening options. Like Cologuard, it can be completed at home and requires a full stool sample, but it combines a FIT with testing of eight RNA biomarkers in the stool. In a study, ColoSense identified 94% of colorectal cancers and 46% of advanced polyps.

Blood-Based Tests

The list of available colorectal cancer screening options has grown with the U.S. Food and Drug Administration (FDA) approval of two blood-based tests: Shield in 2024 and SimpleScreen in 2026. These tests look for alterations in cell-free DNA circulating in the blood that are indicative of colorectal cancer and polyps.

In clinical trials, the Shield and SimpleScreen tests detected 83% and 79.2% of colorectal cancers, respectively, although they were both somewhat less effective at detecting stage 1 cancers. Dr. Macaron emphasizes that both blood tests are significantly less effective at identifying advanced precancerous lesions, with detection rates in the clinical trials of 13% for Shield and 12.5% for Simple Screen.

Given these limitations, “At this time, blood‐based tests should be recommended only to individuals who decline or do not complete preferred screening tests,” the ACS notes in its guideline update.

“So, if someone would not undergo any screening other than a blood-based test, then it makes sense to offer it and accept its limitations because we’re taking that person from being unscreened to being screened,” Dr. Macaron adds.

How Do You Choose the Right Screening Test?

The American Cancer Society recommends considering these factors when deciding on a colorectal cancer screening method:

• How often you’ll need to repeat the test (see the table, “ACS Recommended Screening Intervals”).
• How well it detects cancer and precancerous growths; review with your healthcare provider.
• Whether bowel preparation and/or any dietary restrictions/changes are required.
• Whether sedation is needed and whether you’ll need to take the day off of work.
• Possible risks or complications (review with your doctor).
• Insurance coverage and potential out‐of‐pocket costs.

What Happens If Your Screening Test Is Abnormal

A positive (abnormal) result on a non-colonoscopy screening test does not necessarily mean you have colorectal cancer, but it does require further evaluation, the ACS notes. So, any positive results from these tests require follow-up with a timely colonoscopy to complete the screening process, preferably within six months, according to the ACS guidelines.

Some data suggest that a significant number of people with positive stool- or blood-based screening tests do not undergo follow-up colonoscopies. In one study, the participants with positive FOBT results who failed to have a follow-up colonoscopy had a fourfold greater colorectal cancer incidence, compared with the general population (JAMA Network Open, March 19, 2026).

“Repeating a non-colonoscopy test after a first positive test is not recommended. This is a common question I get from patients,” Dr. Macaron advises. “Once it’s positive, you have to have a colonoscopy to have an accurate visualization of the lining of the colon.”

What Are the Benefits and Risks of Screening

Each colon cancer screening method has pros and cons you should consider when weighing your options. As Dr. Macaron and the ACS emphasize, what matters most is that you undergo regular screening, regardless of the test you choose.

“We know that the overall incidence of colorectal cancer is going down, and death from colon cancer is going down. That’s largely due to screening,” she says. “Still, about a third of Americans who are eligible are not screened, and about two-thirds of colon cancers that are detected are a result of missed opportunities to detect precancerous lesions. I think most of that will improve with increased uptake of screening.”