Cologuard vs Colonoscopy: Which test is best?
Cologuard is a new alternative to colonoscopies. But is Cologuard a reliable replacement for colonoscopies?
Colon cancer is the second leading cause of death in the US. This is a really sad statistic considering it is the most preventable cancer. With regular screenings, you can reduce your chances of getting colon cancer significantly. But colonoscopies sound pretty intimidating to most. 
Cologuard seems to be the answer for those who don’t like the idea of a colonoscopy or for sensitive populations who cannot receive a normal colonoscopy. Dr. Ken Brown and Eric Reiger talked about colonoscopy vs cologuard on an episode of the Gut Check Project. Find out what a gastroenterologist has to say about this potential alternative: is it reliable, is it for everyone, or is it a quick cash grab?
Changes to Colon Cancer Screenings
Colon cancer has become an increasingly common cancer diagnosis. Screenings for colon cancer used to begin at age 50. The age for colon cancer screening has dropped to 45 considering more people are being diagnosed at younger ages.
Millennials are the first generation who have more diagnoses of colon cancer than their parents.
With all of these changes in the age range of colon cancer, it’s not a surprise that more ways to diagnose colon cancer have come to the market.
During the covid pandemic shutdowns, doctors were unable to give colonoscopies. However, knowing how many people are ending up with colon cancer, Exact Sciences knew they could fill this gap by creating an at-home colon cancer testing kit. This is how Cologuard came to the market.
What is Cologuard?
Cologuard is a non-invasive, at-home colon cancer screening kit. Cologuard is an FDA-approved test for individuals who are at average risk of having colon cancer. Anyone who is high-risk should not use Cologuard and should receive colonoscopies only.
With a doctor’s prescription, you can go to the website and order your Cologuard which will be sent to your house.
Once you receive your Cologuard box, you send in a stool sample to be tested. Cologuard tests for abnormal DNA and blood in your stool. There are other at-home screening tests, but they don’t check for the abnormal DNA which is what puts Cologuard ahead of these other tests.
Tests that come up positive for abnormal DNA or blood in the stool may indicate cancer or precancerous cells. However, there have been false negatives and positives that happen.
If you have any of the following symptoms or histories, you should not use Cologuard instead of a colonoscopy:
- Family or personal history of colon polyps or cancer
- Diarrhea or constipation
- Abdominal pain or cramping
- Change in shape, size, or consistency of stool
- Blood in stool
- Rectal bleeding
- Inflammatory bowel disease
Anyone experiencing these symptoms who uses Cologuard often has a false positive result.
If you get a positive result, you must follow up with your doctor and get in with a gastroenterologist to get a colonoscopy to check for polyps or cancer and proceed with treatment.
If you get a negative result, you don’t need to do another Cologuard screening for 3 years.
What is a colonoscopy?
A colonoscopy is a procedure done in the office by a gastroenterologist. The doctor will use a scope to visually see the inside of your colon and rectum. There is a preparation period before receiving a colonoscopy. You will drink a liquid that will make you evacuate all the contents of your digestive tract. This allows a clear path for your doctor to see what is going on.
During this procedure, doctors can remove polyps, abnormal cells, or anything else that looks questionable and needs to be tested or removed. Doctors find precancerous cells and cancers in this way. The removal of these cells is a form of cancer treatment and is sometimes the only thing someone needs to go from having cancer to being cancer-free.
Colonoscopies are the gold standard for finding colon cancer and receiving a true diagnosis.
Doctors are tested for the quality of their procedures by ADR (adenoma detection rate). This ensures that the doctors are paying close attention during the colonoscopies that they give.
If your colonoscopy comes back negative, you don’t need another colonoscopy for another 10 years.
Cologuard vs Colonoscopy: Which colon cancer test is best?
Since colonoscopies can give you accurate results on where the polyp is, what size they are, and if they are cancerous they are the gold standard and the best cancer screening option. Since they can also remove polyps during the colonoscopy, this makes it a superior screening because everything happens all at once.
If you test positive with Cologuard, you need to get a colonoscopy anyway. This means that you need to get into a gastroenterology clinic, which are typically booked out for months in advance. During this time of waiting, you’ll likely have increased anxiety which can promote disease progression — whether you have it or not. Remember, Cologuard commonly has false positives and negatives.
With a colonoscopy, you have the test date already in place and don’t find out your results until your appointment, which helps save you a lot of stress.
But let’s look at specifics when it comes to Cologuard and colonoscopy.
Statistics of Accuracy: Cologuard vs Colonoscopy
Cologuard’s website provides statistics that are more accurate compared to other at-home testing kits. When going to doctors, the sales reps tell them that it is essentially the same as a colonoscopy when it comes to accuracy.
However, the site also says that if you get a positive result you must still go for a colonoscopy. Which warrants the question, is it worth it to use this method of testing in the first place if you still need a colonoscopy?
Dr. Brown has seen approximately 120 people in his clinic who tested positive with Cologuard. 0 of these people had colon cancer when tested with their colonoscopy.
When looking at data, Cologuard’s results indicate that it is 92.3% accurate in its sensitivity for detecting colorectal cancer. While it was 86.6% accurate when ruling out the potential of colorectal cancer. These statistics sound great, but when this study was followed by UpToDate (a program that follows studies to ensure they remain true) the data was quite different.
UpToDate found that colonoscopies are 75% accurate when it comes to small polyps, 85% accurate with polyps that are 6-9mm, and 95% accurate in large and cancerous polyps. The remaining 5% are typically abnormal situations.
UpToDate found that for Cologuard, its accuracy is only 17% when polyps are small, 17% when polyps are medium (6-9mm) sized, and 42% with cancerous or large (greater than 1cm) polyps.
Based on the true data, this means that a significant amount of people are going to be incorrectly diagnosed. If they have polyps and are told it’s negative, they have 3 years of a growing polyp that could have been removed. This means that if it is cancerous it can become much worse in these 3 years.
How insurance works with Cologuard and colonoscopies
Insurance will cover both Cologuard and colonoscopies. They are deemed routine exams that everyone must get. However, if you use your ‘routine’ exam for Cologuard and it comes back positive, you have to pay for a diagnostic colonoscopy which isn’t covered by insurance as routine. This means you’re paying more for this test.
Remember, there are a lot of false positives and negatives. So you could be paying this extra cost for no reason when you could have used that routine exam for a real colonoscopy in the first place.
This alone may make you want to get a regular colonoscopy. Plus with regular colonoscopies, you get it done and then don’t need another one for 10 years as long as it is negative.
Some people are at high risk and should only get colonoscopies if they are absolutely necessary. In these cases, your GI doctor may suggest you use Cologuard instead. Dr. Brown himself has cases where he prescribes Cologuard for people. However, if you can, getting a real colonoscopy is always going to be the best option for colon cancer screenings.
So please consider this information when it comes time for you to test yourself for colorectal cancer. Colonoscopies are the only true way to take care of your screenings.