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Cologuard® vs. Colonoscopy: Which test is better?

Doctor about to perform colonoscopy

In the US, colorectal cancer is currently the second leading cause of cancer deaths in men and women combined. Virtually all health professionals agree that screening average-risk people starting at age 45 for colorectal cancer is the best way to prevent this disease. There are a few highly effective tools available for colorectal cancer screening: This article will focus on the two most popular tests, colonoscopy and the Cologuard test.

Most people are familiar with colonoscopy, but in case you’re not…colonoscopy is a safe 15-20 minute outpatient procedure that is done using sedation (so it’s painless) that entails using a flexible scope inserted in the rectum (the end part of the colon) and carefully advanced to the cecum (the other end of the colon) to inspect the entire colon lining for the presence of polyps, tumors, and other abnormalities. A polyp is a “precancerous” growth that is common and if not removed can slowly grow and eventually may turn into colon cancer. During a colonoscopy, the doctor can both find polyps and remove these polyps at the same time. Therefore colonoscopy can both diagnose cancer and polyps, but more importantly colonoscopy can prevent colorectal cancer from occurring in the first place by removing precancerous polyps years before they would have otherwise become cancer. A normal colonoscopy typically does not need to be repeated for 10 years. If polyps are found and removed, a colonoscopy will be recommended sooner, to make sure any new polyps that grow will be found and removed before having a chance to turn into colon cancer. Colonoscopy is considered the gold-standard colon cancer prevention test and is the preferred test by most medical societies.

Image of colonoscopy with polyp removal.
Removing a precancerous polyp with colonoscopy.

Cologuard® is a non-invasive, commercially-available screening test for colorectal cancer. The test is ordered by a doctor (typically a primary care provider) and mailed to the patient’s house. When the urge to have a bowel movement strikes, the patient places the Cologuard collection device over the toilet and makes a deposit. There are a few simple preparation steps such as adding in a small amount of liquid that the company provides, and then the entire container of poop is mailed back to the company in the provided packaging. The Cologuard test looks for blood and certain DNA mutations in the stool to determine if a test is positive or negative. A week or so later the doctor gets a report indicating the result. If the test is negative, it only “protects” the patient for 3 years.

So which test is better, colonoscopy or Cologuard?

Well, it really depends on what the goals are…

As a general philosophy, it’s much more effective to prevent a disease from occurring rather than waiting for the disease to occur, then reacting to it. When the disease in question is colon cancer, preventing it starts with healthy diet and lifestyle as well as screening the population at large for polyps, the precancerous growths that cause colon cancer. To have a colonoscopy and remove a significant polyp is akin to stopping a future cancer from occurring in the first place. When effective preventive tests like colonoscopy exist, to wait until a patient has developed cancer and then treating the cancer is like waiting until you have been in a car accident to then put on your seatbelt…it’s too late. Although there are excellent treatments available for colorectal cancer nowadays, including surgery and chemotherapy, treating cancer is not the goal of screening. The goal of screening is to not develop cancer of the colon in the first place!

Typically, when an effective prevention technique exists (like removing precancerous polyps during colonoscopy) the earlier we can screen for colon cancer the better. This is why colonoscopy is the preferred test for younger healthier people starting at age 45. Save a 45-50 year old from colon cancer and you will potentially give that person 30-40+ years of life having not developed colon cancer. Saving a 79 year old from colon cancer is still a commendable goal, however the average 79 year old typically won’t have as many quality years left “in the tank” compared to the average 45 year old.

So why does this philosophical stuff matter when it comes to picking a colorectal screening test? Well, understanding what these tests do helps you understand how to apply the proper test to your individual goal.

If this article is already too long and you just want the bottom line, here it is: Colonoscopy is the superior test for most people, especially “younger” people (age 45-mid 70s). It can both detect and (more importantly) prevent colorectal cancer. It is semi-invasive and less convenient when compared to Cologuard testing. Cologuard is an easier test but plagued by false negatives and false positives. Cologuard does not necessarily prevent cancer, it only detects cancer after cancer has occurred, or at best detects large polyps that are close to becoming cancer. Cologuard should be considered for older patients (age 75+), for patients that may not have the best overall health, or for patients who have specific reasons why they cannot have a colonoscopy.

OK, you asked for it! Here are more details, starting with the Cologuard test:

The study that determined the characteristics of the Cologuard test basically performed the test on almost 10,000 patients at average-risk of colon cancer, and then had the patients undergo colonoscopy as the gold-standard test. The results of the Cologuard test were not available to the patients or the endoscopist at the time of the colonoscopy. The major results of this study showed that the Cologuard test had a sensitivity (the amount of times it picked up colorectal cancer when cancer was indeed present) of 92%. It was far less sensitive for picking up advanced precancerous polyps, at only 42%. It turns out that sensitivity is the main thing we care about in a screening test: we want the test to miss none of the patients who have the disease. A perfect screening test would have a sensitivity of 100%, meaning that if 100 people have colon cancer and have the test, all 100 people will get a “positive” test result, meaning no false negative tests.

Sensitivity isn’t everything however…we also want a test that gives a negative result when someone does not have the disease in question. That is, if you take a group of 100 people that do not have colorectal cancer, a perfectly specific test will have 100 “negative” results, meaning no false positive tests.

What does a positive Cologuard test mean?

First and foremost, a positive result on the Cologuard test means that you need to have a colonoscopy. Not a virtual colonoscopy, or another stool test, or another scan of some sort…you need a real optical colonoscopy. Luckily, only about 4% of people with a positive Cologuard test will have cancer found on colonoscopy. 51% will have a precancerous polyp. The rest (45%) will have nothing found on colonoscopy. So to simplify even further, just a little more than half of people with positive results will have something abnormal (cancer or a polyp) found on colonoscopy.

What does a negative Cologuard test mean?

A negative test means that there is a less than one-percent chance of having cancer found on colonoscopy. However, about 34% of people with negative tests still have precancerous polyps found on colonoscopy, with the remainder (66%) of people with negative Cologuard results having truly negative colonoscopies.

What is immediately apparent from these numbers is that Cologuard rarely misses cancer. However, if we count polyps as a significant finding, there are plenty of false-positive results (45%) and plenty of false-negatives too (34%).

A word on how health insurance companies view Cologuard

While not important to the medical reasoning behind choosing colonoscopy or Cologuard, for some people it is important to note the finances of each test. Either colonoscopy or Cologuard can be considered a screening test, and is typically covered by health insurance plans without an out-of-pocket cost. However, if a Cologuard test is positive (remember that 45% false positive rate discussed above), the insurance company now views the necessary colonoscopy as a diagnostic colonoscopy, not a screening colonoscopy. Diagnostic tests often have an out-of-pocket responsibility for the patient and in the case of a colonoscopy this can be in the thousands of dollars range. This is something rarely discussed when ordering a Cologuard test in the primary care setting, but that we often need to educate patients about when it’s time to book their colonoscopy to follow up a positive Cologuard test.

What about colonoscopy? Are there any downsides?

In good hands, colonoscopy is an excellent test—it’s the best test we have in the fight against colon cancer. However, no test is perfect and colonoscopy is no exception. Even though colonoscopy is the gold-standard test, here are some of the negative things to know about colonoscopy.

Colonoscopy requires a bowel preparation, meaning you have to take either a liquid prep or pill prep to clean out the colon the day before. It’s not painful, but prepping for a colonoscopy is far from a good time. Colonoscopy has small but real risks, such as bleeding, infection, perforation of the bowel, and anesthesia problems. However these risks are very rare, and in with a skilled team the risk of a serious complication is far less than 1 in 1,000 procedures. Colonoscopy also has a miss rate for polyps and even cancer. It is very hard to define an actual number of missed lesions because it’s difficult to perform a study on the gold-standard test (colonoscopy) as there is no better test to compare it to. That being said, colonoscopy can miss small polyps around 20% of the time, and can even miss cancer a few percent of the time. The devil is in the details however: Missing a significant lesion during an outpatient screening colonoscopy in a properly prepped patient (meaning the patient did the bowel cleanse effectively) with a doctor that performs high-quality colonoscopy (meaning the doctor spends adequate time and uses excellent technique to find and remove polyps) is quite a rare event and is something that is difficult to study given variations in quality practice between doctors even in the same community or hospital system.

Here is a quick pros and cons table to help clarify all of the above

MeasureColonoscopyCologuard®
Prevention of colon cancer?YesNot really
Repeat a normal test every10 years3 years
Overall convenienceBowel prep and 1 day off workNo prep but have to handle stool
Overall invasivenessModerately invasiveNot invasive
AccuracyVery accurateNot very accurate
Biggest upside of the testBetter cancer prevention and accuracyEasy and can do it at home
Biggest downside of the testBowel prep and less than 0.1% chance of complicationsLots of false positives that will require a colonoscopy anyway

How do I choose between colonoscopy and Cologuard in my practice?

I typically reserve Cologuard testing for patients that just need to know if they have cancer right now, and are not in good condition to undergo colonoscopy due to other major health issues. A patient that has not been screened recently who is approaching 80 years old, and who has one or more major cardiovascular or pulmonary issues is a good candidate for Cologuard testing. For pretty much everyone else, colonoscopy is by far the better test.


References:

Imperiale TF, Ransohoff DF, Itzkowitz SH, et al. Multitarget stool DNA testing for colorectal-cancer screening. N Engl J Med 2014;370:1287-97.

Cologuard website: http://www.cologuardtest.com/current-patients/how-to-use

Cologuard is a registered trademark of Exact Sciences Corporation.

VIDEO: Colonoscopy prep with pills only! All about Sutab!

Doctor holding Sutab pill

The colonoscopy prep experience is by far the worst part of the whole procedure. For years, patients have been asking “Isn’t there a better way to do the prep?”

Well, now there is! There is a prescription bowel prep called Sutab that I have been using for the past two years for most of my colonoscopy patients. Sutab comes in a kit which includes 24 pills and a container to measure the water, and it couldn’t be any easier to take. Most of my patients that have used the older liquid preps in the past are pleasantly surprised after using Sutab for the first time!

Here is a short video I made showing you how to use Sutab. I also cover the diet you should follow to make sure your “clean out” is as clean as possible, and how to handle the common side effect of all bowel preps…nausea.

VIDEO: See how a gastroenterologist does the colonoscopy prep!

In this video, Dr. Gandolfo will show you what NOT to do if you want to have an easier colonoscopy prep experience. He will also share five tips to help you handle the pre-colonoscopy clean-out like a champ!

If you want more information about colonoscopy, be sure to download our free ebook today! It will answer any question you can think of about colonoscopy, even questions you didn’t know you had!

Click the picture of the book below to get it delivered to your inbox!

Get Dr. Gandolfo’s free ebook today!

If you’ve got questions about colonoscopy, this is the book you need to read!

Everything You Need To Know Before Your First Colonoscopy is packed with everything you could ever want to know about having a colonoscopy! I will take you step-by-step through the procedure, and answer all of the common questions that I usually get from patients about the test.

Here is the table of contents from the book:

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Help! The colonoscopy prep isn’t working! What can I do?

Bowel prep, or that stuff you need to drink to get cleaned out for your colonoscopy, is never something that one looks forward to doing. You knew that drinking the prep was a necessary evil to ensure a high-quality colonoscopy, but what do you do if you followed all the instructions but the prep simply didn’t work?

If you’re reading this while in the midst of a potentially failed bowel prep don’t despair! There are many ways to salvage a bowel prep and still have a safe, high-quality colonoscopy the next day. It all depends on what time you take action; If you wait until 2 hours before the procedure is scheduled than yes, it’s probably too late to do much. However, if you’re already having issues the night before you can totally recover from this and be fine. This is what I usually recommend, based on the issue at hand:

“I drank the first dose of the prep and nothing happened.” I usually tell patients to wait several hours before panicking. If you have waited 6 hours and there is no bowel activity whatsoever then at that point I would recommend taking either 10 mg of bisacodyl by mouth, or giving yourself an enema. If you’ve done all that and still nothing happens, then it’s probably time to call your doctor and ask for suggestions.

“I drank the first dose of the prep but vomited most of it up.” Unfortunately, you will need more prep then. This usually requires a phone call to the doctor explaining the issue and often an alternative prep is recommended. In selected patients, I would usually recommend Miralax prep or using magnesium citrate instead–both of which can be purchased over the counter.

“I can’t drink the first dose of the prep because it tastes horrible! Yuck!” Try putting the prep in the refrigerator and making it as cold as you can tolerate. Much of the taste disappears when you really chill the prep. You can also call your doctor to see if an alternative prep is an option for you. Ultimately this is also a case of mind-over-matter…it’s unpleasant but sometimes you just have to do it anyway!

“I drank both doses of the prep and my bowels are still not clear” This is a common issues with some bowel preps. It really depends on what time this happens. If you did all the prep the night before, then there is plenty of time to follow the prep with a bottle of magnesium citrate and a large volume of clear liquids. If you notice that you are not clear the morning of the procedure, you can still drink magnesium citrate but really need to finish drinking it about 4-5 hours before the procedure is scheduled to start. This gives it enough time to have an effect, and also keeps you well within the 2 hours safety window for ingestion of clear liquids with respect to receiving anesthesia. However, if the procedure time is close (2-3 hours away)  and you’re still not clear, then the only real option is to give yourself an enema or two. You can always reschedule the procedure if you have to, but realize that you already completed the bowel prep and will therefore have to do the entire prep again if you need to reschedule!

Happy prepping!

Watch the YouTube video here!

American Cancer Society recommends colorectal cancer screening to begin at age 45

On May 30, 2018, the American Cancer Society (ACS) released new guidelines regarding colorectal cancer screening for the average-risk individual. The big news is that they now recommend that screening for colorectal cancer begin at age 45 rather than age 50. This reduction in the starting age was in reaction to recent data showing that colon cancer is increasing in younger Americans for unclear reasons. By screening people at a younger age, the hope is that we can detect and prevent colon cancer in more people.

The ACS states that 20% of new cases of colorectal cancer occur in the younger-than-55 crowd. Furthermore, despite a general downward trend in colorectal cancer in the over-50 population, the risk is actually rising slightly in the subgroup of people aged 50-54. These are the cases of cancer the new guidelines are trying to prevent. The ACS is pragmatic in acknowledging that people don’t typically sign up for a colonoscopy exactly on their fiftieth birthday…in fact many wait a few years or more after age 50 to get screened. By pushing the starting age up by 5 years there will likely be a benefit to these patients who would otherwise be late to the colonoscopy party.

The consequences of these recommendations are potentially huge. If these guidelines are followed, an estimated twenty million additional people are now eligible for colon cancer screening. However, the ACS does not specify any one best choice for colorectal cancer screening and states that colonoscopy, stool DNA testing (Cologuard), virtual colonoscopy, and stool testing for occult blood with Guaiac-based tests or FIT testing are all equivalent. I think that by now we know that all tests are not really equivalent, with colonoscopy being the gold-standard test, but with millions of people not getting any type of screening at all, any test is better than nothing.

“My thirties are going great! And in a few short years, I’ll need my first colonoscopy!”

A few caveats about these new recommendations:

  • The ACS states that the recommendation to start screening at age 45 is a qualified recommendation, meaning that there are clear benefits of screening at this younger age but there is less certainty about the exact risk-to-benefit ratio of the recommendation. This is opposed to a strong recommendation, which means the benefit is clear and almost everyone should do it. (Beginning screening at age 50 remains a strong recommendation from the ACS.)
  • Other guideline-producing organizations such as the US Preventive Services Task Force (USPSTF) have not changed their recommendations for colorectal screening, which still remain at age 50 to start.
  • Just because the American Cancer Society changed the recommendation to age 45, doesn’t mean that insurance companies are going to cover the testing! This is perhaps the most interesting part of these new guidelines…who is going to pay for this?
  • Starting screening earlier is definitely going to pick up and prevent more cancers than starting later, however is 45 the best age to start? Surely starting at 44 would pick up even more cancers! I bet starting at 40 would pick up even more than that! What I’m trying to illustrate is how there can be a slippery-slope with these type of recommendations: You will always find more cases of colorectal cancer if you start looking for it in younger and younger people. At what point do the risks of screening more and more people start to outweigh the benefits? Only time and more research will help answer this question.
  • What about the truly early-onset colorectal cancer patients? These are patients diagnosed in their twenties and thirties…how do we detect them before they develop the disease? I doubt anyone will recommend starting routine screening colonoscopies at age 18! This very young onset colorectal cancer may just behave differently than the typical sporadic colon cancer that develops later in life. We need to develop different ways of finding the young patients at risk, and determine why the risk is rising in the younger population.

A Gastroenterologist Cheats on the Colonoscopy Prep

toilet paper

I’ll just start out by letting you know that I had mixed feelings about posting this. Not because I’m embarrassed to publicly discuss my colonoscopy experience (weirdly enough, I am OK with that part), but because I don’t want to be responsible for people interpreting what I’m about to disclose far too liberally and ruining their pre-colonoscopy cleanout. So please read on, but don’t push the limits too much. Failing to achieve a good bowel prep will require you to repeat the exam and prep again, and nobody wants that to happen!

For the past year or so I have been having minor IBS-type symptoms on and off, mostly related to stress or periods of poor diet. As a gastroenterologist, I started getting into my own head and worrying that I had some rare or catastrophic disease (the availability heuristic is real!) Part of me knew that if the test was normal, I would probably feel better just with that knowledge alone. I’d also be lying if I said that I wasn’t just a little curious about the whole process too. I either talk to people about colonoscopies or perform them for most of my waking hours; shouldn’t I also have some first-hand experience to reference for my patients?

So I scheduled a colonoscopy and requested Suprep bowel prep. I choose Suprep because it is what I usually give out to patients…I’ve noticed that most people seem to complain the least about the taste of Suprep when compared to most other preps. That’s not to say that the other preps are inferior…I use them interchangeably. However, I wasn’t about to get two or three more colonoscopies just to test out all the preps, so the Suprep experience is what you get to hear about!

suprepI was given the usual instructions for split-dose bowel prep: 1) Clear liquids only the entire day prior to the procedure; 2) Take the first dose of prep at 5 PM and the second dose of prep 5 hours before the procedure start time; 3) Nothing to eat or drink after the second dose of prep. Pretty standard stuff, these are the instructions I usually give to my patients. Following this will lead to a good or excellent bowel prep in the vast majority of people. But what if I told you that I did something different but still achieved an excellent clean-out?

toasterI cheated on the prep. I ate solid food the day before. Now before anybody gets too excited, I ate a very limited and small amount of food, but it made a huge difference in the ability to tolerate the entire process. The following is my “justification” for my cheating, other than the obvious reason of “I was hungry.” I wake up around 5:00 AM or earlier every day. I usually wake up starving and if I don’t eat something within an hour or so of waking I usually feel weak and like my head is spinning. I’ve been this way as far as I can remember, even back in elementary school. I had a long day ahead of me at work, and knew that without some calories in me I would crash in the mid-morning while doing procedures and not be able to function well. “It’s for the patients,” is what I told myself. I almost believed it, too!

So that morning I ate a good-sized bowl of plain vanilla yogurt (no toppings, nuts, fruit, etc.) I also had a few pieces of white toast with butter. We usually don’t have white bread in the house, but we were lucky to have an unseeded loaf of Italian bread from the night before that I toasted in the toaster and buttered up. For lunch, I had a huge gelato without any nuts or toppings. Throughout the day I drank black coffee and plenty of clear liquids.

ice creamI got home around 6PM that day (a little later that the recommended 5PM start time) and began drinking the prep. I mixed the first part of the prep with water as recommended and took a sip. Thinking that I’d be really slick, I used a straw to try and bypass my taste buds. “Not terrible,” I thought to myself, relieved that this process wasn’t going to be as bad as many patients made it sound. The prep tasted like a mixture of seawater, dish soap, and grape cough syrup…yum! A few sips later and I was rethinking this whole thing…the cumulative effect of drinking the prep made each sip taste grosser than the last. After drinking about one-quarter of the first 16 ounces of the stuff, I put the container in the fridge and took a 10-minute break to pace around the house and rethink my strategy.

Going back to the prep in the fridge, I took a few more sips through the straw. Why was it taking so long to drink this stuff? If this were water I could have drank the whole thing in five minutes. I think the straw is actually slowing the process down. I ditched the straw and was able to drink the prep much faster. A few gulps later I was half-way done with the first round. I put the container back in the fridge since the colder the prep was the less bad it tasted. It’s now about 6:20 PM and I suddenly felt a strange grumbling in my lower abdomen.

I was surprised at how fast this stuff works! I figured it would take an hour or so to have any effect, or at least give me some warning first. I was wrong on both counts! With 8 oz. of the nasty stuff down so-far, I was lucky that my bathroom was only a few steps away! Immediate watery diarrhea was the result. The thing I wasn’t expecting was the total lack of pain, cramps, or any discomfort whatsoever. It was as someone just opened the faucet, then closed it again. Magic!

I finished the rest of that evening’s prep over the following 20-30 minutes in between several other sprints to the bathroom. The prep was definitely easier to drink when cold straight out of the fridge. It was about 7PM and the bowel movements were coming fast and furious now. I also noticed that I was incredibly thirsty all of a sudden. I chugged 32 ounces of room temperature Gatorade in about five minutes flat. I wanted more, but only had tomorrow’s ration in the house. Therefore I drank a glass or two of water. By 9PM, all was quiet. I mixed tomorrow morning’s prep and put it in the fridge to chill overnight. I woke from sleep around 1AM for one more small bowel movement, but it was no big deal. I actually got decent sleep.

The next morning, I woke up at my usual time of 5AM. I drank 2 cups of black coffee as soon as I woke up. This was followed by another 16 oz. of Suprep over the next 45 minutes. I would gulp down about 4 oz. at a time, then rest for 10-15 minutes and repeat until done. This time, the bowel movements started immediately after taking the first bit of the prep and were mainly yellowish water. Another 32 oz. of Gatorade down the hatch and the process was complete. The last 2-3 bowel movements were literally clear water, like as clear as the water that comes out of the faucet. Cool, I did it!

Now would be a good time to talk about a study from a few years back. Thinking that improving the tolerance of the prep would remove one of the classic barriers for some people to do colonoscopy as well as decrease the number of broken appointments and inadequate preps, researchers randomized patients into two groups: One group received a clear liquid diet the entire day prior, and the other was able to eat a light breakfast and lunch with several food restrictions the day prior. Both groups then completed the standard bowel prep. The study showed exactly what we would expect: The people who starved all day were miserable, the people who ate a little were less miserable, and the quality of the bowel preps achieved were the same between the groups! The most interesting finding was that the group of patients who were restricted to only having clear liquids cancelled their appointments more than twice as frequently as the patients that were allowed to eat just a little. Hunger is a powerful force to compete with!

Now before you eat a bacon cheeseburger with fries, corn on the cob, and a salad the day before your colonoscopy, it’s very important to understand that these subjects (and yours truly) ate a very limited diet the day before the colonoscopy. Fibrous foods such as any fruits or vegetables are not allowed. Seeds, nuts, whole grains, fresh or dried herbs/seasonings, popcorn, and the like are definitely not allowed. Corn is probably the worst thing one can eat the day before having a colonoscopy!

no cornWhat kind of foods are OK to eat the day before the colonoscopy? Low residue foods (low roughage) are ideal; these are processed flours (white bread, etc.), white rice, pasta, yogurt, gelato, and related snacks, eggs, lean meats, and other foods. A light breakfast is fine. A light snack around lunch time is OK too, but after that it’s clear liquids only. That means “dinner” is clears only: You don’t want food and bowel prep in your stomach at the same time, trust me.

So back to the title of this article: A gastroenterologist cheats on the colonoscopy prep and wins! Did I really cheat? I guess not, since it seems that research backs up what I did! But did I win? Can you ever call getting a colonoscopy “winning?” I guess it depends on the findings. I did, however, have an excellent bowel prep!