Colon cancer is the third most common cancer in the United States, with more than 150,000 people diagnosed each year.[1] The United States Preventative Services Task Force (USPSTF) lowered the guidelines for colorectal cancer screening from age 50 to 45 in early 2023. This was done after findings from a study by the American Cancer Society showed that more than 10% of colorectal cancers occur in people under age 50. [1,2]
Several options are available for colorectal cancer screening. This article delves into the differences between two commonly used testing modalities, Cologuard® and colonoscopy, and will help you determine which colorectal cancer screening option is best for you.
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Understanding Colorectal Cancer Screening
Colorectal cancer occurs when these cells grow in the colon or rectum. [3] Colorectal cancer is very common, affecting about 4% of people during their lifetime, and is the second most common cause of cancer-related death in the United States. [4,5]
Colorectal cancer is usually asymptomatic, especially in its early stages. If it does become symptomatic, symptoms may include: [6]
- Changes in stool caliber
- Diarrhea
- Constipation
- Bloody stool
- Abdominal pain, cramping, or gas
- Feeling like the bowels don’t completely empty
- Fatigue or weakness
- Unexplained weight loss
Early colorectal cancer diagnosis generally results in better outcomes. With colorectal cancer screening, abnormalities can be detected even before those abnormalities turn into cancer. A study in the Journal of the American Medical Association found that routine screening may decrease the mortality rate from colorectal cancer by 14%.[7]
Cologuard®: An Innovative Screening Method
Cologuard® is a multitarget stool DNA test that the US Food and Drug Administration (FDA) approved in 2014. This test is indicated for average risk screening in people aged 45-75.[8] If the results are normal, then this test should be repeated every 3 years. However, if the results are abnormal, then a colonoscopy is recommended.
Some of the advantages of using Cologuard® instead of other screening tests include:
- Unlike some other colorectal cancer screening options, Cologuard® does not require dietary restrictions, medication restrictions, or colon preparation.
- Cologuard® is non-invasive and can be performed in the comfort of your own home.
- With Cologuard®, once you receive your kit, you collect a stool sample, scrape it, and mail it back for analysis.[9] The lab will analyze the stool sample for cells from the colon wall and examine these cells for DNA abnormalities. [10]
Cologuard® is not a replacement for colonoscopy and is not appropriate for everyone. It should not be used for people with: [11]
- blood in their stool
- a history of colorectal cancer
- a history of colon polyps
- a family history of colorectal cancer in a first-degree relative diagnosed at or younger than 60 years
- two or more first-degree family members with colorectal cancer diagnosed at any age,
- a known genetic cancer syndrome
- inflammatory bowel disease
This test has a significantly higher false positive rate than FIT testing alone, meaning that many people may have an increased chance of going through a colonoscopy unnecessarily.[8]
Cologuard® is less expensive than a colonoscopy, estimated at $680, but it is more expensive than some of the other non-invasive testing options.[8] The false-positive rate is around 13%, and the false-negative rate is 8%.[12]
Colonoscopy: The Gold Standard
Colonoscopy has been the gold standard test for colorectal cancer screening since the 1990s. The test has been available since the late 1960s.[13]
What to expect:
- A colonoscopy involves taking medication (prep) to empty and clean your colon the day before the procedure.
- Once you arrive at the surgery center or hospital, you will have an intravenous (IV) inserted for sedation. Generally, either conscious sedation using medications such as fentanyl and versed are used, or monitored anesthesia care (MAC) with a medication such as propofol can be administered. With sedation, you won’t remember anything or have any discomfort during the procedure.
- Once you’re sedated, the endoscopist will put a flexible camera into your rectum and advance it to the end of the colon, the cecum, while inflating your colon with air.
- The endoscopist will then examine your colon wall while they withdraw the scope.
- If any abnormalities are seen, such as polyps or inflammation, biopsies can be taken. In many cases, polyps can be removed during the colonoscopy.
- Colonoscopy is an outpatient procedure, which means you usually go home within a couple of hours of the procedure. There are not typically any dietary restrictions, though you can’t drive for 24 hours after sedation.
- After a colonoscopy, you can expect some gas pain because air is inserted into your colon to allow the endoscopist to see your colon walls.
Colonoscopy has a high accuracy for identifying abnormalities and has the advantage of being able to remove polyps before they have the chance to advance to colon cancer. Colonoscopies are more than 98% accurate at detecting colon cancer.[14]
The disadvantage of colonoscopy is that it is a more invasive procedure than some other options. It can also be uncomfortable and carries more risk than less-invasive options. Some of the potential complications of colonoscopy include reaction to sedation, bleeding, or tearing a hole in the colon wall (perforation).[15]
Comparing Cologuard vs Colonoscopy
Cologuard®:
- Has a 92% sensitivity for detecting colon cancer.
- According to the company that makes the test, the false-positive rate is around 13%, though some studies have estimated it to be as high as 45%.[16] This means that 13-45% of the time if someone has a positive test, there will not be an abnormality present.
- It is a less invasive screening option. This may increase screening rates in people who otherwise would not have completed the recommended colorectal cancer screening.[17]
- No preparation is required.
- It is less uncomfortable than a colonoscopy.
- It doesn’t require time off work because no sedation is required.
- It is also less expensive than a colonoscopy, which is estimated to cost around $680.
Colonoscopy:
- The sensitivity of colonoscopy is above 98% for colon cancer.[14,18] Some researchers and physician groups have expressed concerns over the positive predictive value of the Cologuard® test due to the rate of false positive tests.[16]
- Colonoscopy can be used on any patient, including those with symptoms, those that are in higher risk groups, and people with a history of colorectal cancer.
- Colonoscopy is the most accurate test for colorectal cancer screening. It is more expensive than other testing options, costing over $1000.[19]
Insurance and Medicare coverage may vary depending on deductibles and co-pays. The Affordable Care Act requires insurance companies to cover cancer screening tests recommended by the USPSTF.[20] Most people will not have out-of-pocket costs for these tests, though you should check with your insurance company about what costs you may incur.
Expert Opinions and Guidelines
- The American Cancer Society (ACS) and the USPSTF recommend that average-risk individuals undergo screening for colorectal cancer beginning at age 45.[2,21]
- Colorectal cancer screening should continue until at least age 75 at intervals that depend on which option you’ve chosen for screening.
While the accuracy rates of different screening methods vary, the ACS and USPSTF acknowledge that getting screened is more important than which test you choose if you are at average risk.
Case Studies and Real-World Examples
Cologuard® has several testimonials available from people who have had their colorectal cancer detected by the study and have survived cancer as a result.[22]
Many people who have had colonoscopies note that the experience was not as uncomfortable or unpleasant as anticipated.[23]
Cologuard® and colonoscopy are both good options for colorectal cancer screening, but colonoscopy is still the gold standard.
If the Cologuard® test is positive, following through with a colonoscopy is vital. Cologuard® can’t prevent cancer by removing polyps, while a colonoscopy can. Detecting colon cancer is a process, so additional testing with colonoscopy is necessary if one of the other screening tests is positive.[24]
Making an Informed Decision
There are many options for colon cancer screening. Which option is best for you depends on several factors. High-risk individuals should have a colonoscopy, but for average-risk individuals, more choices are available.
People at high risk for colon cancer include those with: [25]
- A personal history of colon cancer
- A first-degree relative of colon cancer diagnosed at a young age
- Multiple first-degree relatives diagnosed at any age
- Symptoms of colon cancer
- Inflammatory bowel disease
- A genetic syndrome that increases their cancer risk
The test you choose may depend on your lifestyle. Colonoscopy only needs to be performed every 10 years if it is normal, while Cologuard® is done every 3 years, though the latter doesn’t require any preparation or sedation and can be done from the comfort of your home. Your healthcare team can help you determine which option is best for you.
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Key Takeaways
- Colorectal cancer screening should start at age 45 in average-risk individuals.
- Cologuard® is less invasive and less expensive than colonoscopy but may also be less accurate.
- Getting screened is more important than deciding which test is used for average-risk individuals.
Colorectal cancer screening can detect problems early and can significantly reduce the risk of death from colon cancer. If you’re over the age of 45 and you have not had colorectal cancer screening, talk to your healthcare provider today about which screening option is best for you.
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