Colonoscopies: America’s gold standard, while Canada says they’re not justified

Alan Cassels, who is a journalist and pharmaceutical policy researcher at the University of Victoria, British Columbia, reflects on the differences between Canadian and US guidelines on colon cancer screening and why that disparity isn’t being reported on. 

iStock_000003979292_SmallDo borders really exist in medicine, where the mere act of crossing political boundaries changes what screening programs are recommended? It seems that they do exist, and they’re well guarded.

Generating numerous headlines in major Canadian papers such as the National Post, The Toronto Star, Globe and Mail and Reuters, the Canadian Task Force on Preventive Health Care came out this week with new recommendations on colon cancer screening, essentially saying that routine colonoscopies were not justified. By contrast, in the United States, the U.S. Preventive Services Task Force (USPSTF) 2015 guidelines say that adults aged 50–75, should have a colonoscopy every 10 years; FIT (fecal immunochemical testing) or gFOBT (guaiac fecal occult blood testing ) annually or flexible sigmoidoscopy every 10 years plus FIT annually.

For this age group the Canadian Task Force says there is insufficient evidence to justify using colonoscopy for routine screening for colorectal cancer. They recommend patients should undergo the fecal occult blood testing every two years or flexible sigmoidoscopy – a procedure which examines the lower part of the colon and rectum every 10 years. These colon cancer screening guidelines, published in the Canadian Medical Association Journal, are for low-risk people: asymptomatic adults, aged 50 to 74 who have no prior history of the disease, no family history or symptoms such as blood in the stool, or a genetic disposition to the disease.

Despite the significant gulf that separates the Canadian and US recommendations, only a smattering of US news outlets, such as US News and World Report, ventured to cover the new Canadian guidelines.

Why the difference? How can there be such a wide disparity, on an issue with huge patient care and financial ramifications, that goes almost totally unreported on?

Perhaps what happens in medicine in Canada isn’t necessarily big news in the US. Americans have been told ad nauseum that colonoscopy screening is the “gold standard” and that you’d be a fool not to get one. So the fact that Canadians won’t pay for the procedure is their problem — and one that Americans needn’t dwell on. But not everyone in the U.S. thinks this way., for one, has weighed into this debate frequently and vigorously, noting that colon cancer screening news coverage is ‘all over the map,’ with too much unbalanced reporting on the issue. (For a full course meal on US colonoscopy screening journalism, search the HealthNewsReview,org site with the keyword ‘colonoscopy’ where you’ll find nearly 50 related stories and blogs).

Our national differences in screening recommendations aren’t a reflection of the amount of knowledge each country’s teams of screening experts have, but rather an array of scientific, economic and possibly cultural issues that lay behind those recommendations.

For some perspective I spoke to Dr. Maria Bacchus, chair of the Canadian Task Force on Preventive Health Care (Canada’s equivalent to the USPSTF) working group on colorectcal cancer, an independent body of 14 primary care and prevention experts who develop clinical practice guidelines. For Dr. Bacchus colonoscopies have an important role to play in investigating symptoms and follow up, but she said there isn’t enough evidence to suggest they should be used as a first-line screening tool.    

“When we looked at all the evidence, all the randomized controlled trials we wanted to see how it compared to other tests in terms of reducing colon cancer mortality.” There are currently four randomized trials in process and when they report back (which may be up to five or ten years away) “we will have to look at other things.”

As for the difference between Canada’s and the US’s recommendations, she said that the USPSTF would have included observational studies in their analysis of colonoscopy screening while the Canadians did not. She said: “We found good RCT [randomized controlled trial] evidence for the fecal occult blood test and flexible sigmoidoscopy, but not for colonoscopy screening.” 

“When we make a recommendations, we look at the GRADE guidelines, that look at the quality of evidence, the balance of benefits and harms,” she said, adding that the harms of colonoscopy occur infrequently, probably “less than one percent.”  

Other issues contributing to the disparity include acceptability and resources. The invasiveness of a colonoscopy is legendary: it requires prior cleansing and sedation and is uncomfortable for some, inconveniences that may put people off getting that kind of screening. There is a wait list for colonoscopies in Canada and in contrast “the FIT test and flexible sigmoidoscopy are readily available and people between 50 and 74 can go and ask their doctors for them,” said Bacchus.  

Money is also serious issue when you think that the proven methods, the FIT test (which is done at home) and the flexible sigmoidoscopy (which can be done by a GP with light sedation), are much cheaper than colonoscopies delivered by gastroenterologists and others with special training. It’s a whole industry unto itself, and in Canada our system just naturally helps to rein in the profit motive.

How resources are allocated might be more of a factor in the Canadian recommendation, Dr. Bacchus said. “We think is it a wise use of resources–we do have to look at that,” noting that the wait list for colonoscopies in Canada is already long and recommending it as a screening tool would add even more burden to the wait lists.

Dr. James Allison, Clinical Professor of Medicine Emeritus at UCSF and Emeritus Investigator at Kaiser Permanente Division of Research Northern California, has widely published in this area and believes the message about colonoscopies from the Canadian Colorectal Cancer Screening Taskforce is important but must be nuanced.

He says colonoscopy is an excellent screening test, but there is no evidence that it is better at decreasing mortality from or incidence of colorectal cancer compared with a less invasive and less expensive FIT test yearly or every other year and following up with a colonoscopy if the FIT test is positive. If this is done, fewer colonoscopies will be needed and gastroenterologists will have more time to diagnose and care for their very ill patients with chronic gastrointestinal diseases, Allison said. It is a way of managing limited healthcare resources without compromising patient care. If an individual wants a colonoscopy despite the lack of evidence that it is the “best” test, they should be able to have it but, with a copay, he added.

(Anyone in Canada with a positive FIT test –which shows evidence of blood in the stool–would jump right ahead to getting a publicly-subsidized colonoscopy.)

The Canadian approach is supported by other experts in the US such as Dr. Richard Hoffman, one of our medical editors whose opinion has not wavered from an article he wrote five years ago saying that “from a public-health perspective, emphasizing colonoscopy is problematic.”  His article succinctly outlined the problems: “the efficacy of colonoscopy has not been supported with randomized trial data, accuracy is imperfect, procedural quality is variable, complications are not uncommon, endoscopic capacity is limited, procedure costs are high, and many patients prefer alternative tests.”  

I talked to Dr. Hoffman and he came right to the point: “We don’t need to be screening more, we need to be screening smarter,” adding that we need to reserve colonoscopy for screening high-risk patients, such as those with a family or personal history of the disease, and patients with adenomatous polyps—who are at increased risk for colorectal cancer.

In the US the National Colorectal Cancer Roundtable aims to get 80% of the population screened by 2018. Hoffman blogged about the problems with this objective, reminding us that “attempting to screen primarily with colonoscopy will be expensive, risky (complications include perforation and bleeding), and likely not the preferred option of many patients.”

At the end of the day, the public needs good clean information as urgently as we need good clean water. Hopefully the Canadian recommendations will flow more freely across the border, and stimulate even more debate in the US–especially from the US news media. Sadly much of what Americans hear about colorectal screening has been tainted by misinformation about the value of the whole spectrum of screening options.  

International comparisons on medical recommendations are important, and if Americans knew that they were an outlier in the world of colon cancer screening, perhaps that fact alone might stimulate even more healthy debate in the US about the value of screening colonoscopies.  

But then again, being an outlier on health care issues hasn’t influenced Americans before. Not on proton beam therapy, the proliferation of robotic surgery, national spending on health care, or universal health care — to name a few.

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Comments (15)

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February 26, 2016 at 5:42 pm

The differences between the Canadian and the American approach to colon cancer screening are highlighted in this commentary by Dr. Dennis Ahnen & Dr. Aasma Shaukat, just published by the American College of Gastroenterology which represents the private gastroenterologists in the U.S.

Bradley Flansbaum

February 26, 2016 at 7:18 pm

Also, and I say this agnostically, the screening outcome of interest in all our studies concern mortality. Many folks have lesions identified Stage I plus, have resections and chemo, and then survive. A win for FOBT and flex sigs instead of a full scope. However, to offer a shared decision and harms/benefits, we must consider morbidity and quantify the full range outcomes as well.

Also, I am curious you didn’t get a “pro” colonoscopy voice from the USPTF or some fair comparator for balance.


    Gary Schwitzer

    February 27, 2016 at 7:32 am


    Thanks for your note.

    Alan’s piece establishes, starting in the headline, that colonoscopy is the gold standard in the US. It outlines the USPSTF recommendation. When the “comparator” is so well-entrenched, so heavily-promoted, and so well-known, there are times when getting a voice to say that one more time feels formulaic, predictable, and not particularly helpful. This piece was, as Cassels points out, about something that not many Americans may know about. In fact, when I did a Google News search just now using “colonoscopy” as my search term, the top result I get is “Mayo to livestream a colonoscopy to boost screenings.” I’d say that point of view is heard quite often, quite loudly. I think the weight of emphasis with Cassels’ piece was fine.

    Gary Schwitzer

      Bradley Flansbaum

      February 27, 2016 at 6:38 pm

      As always Gary and Alan, thanks for the space to comment.
      A brief response and I will let you have the last word if you choose.
      We don’t need another pro-colonoscopy mouthpiece to shill for the procedure–especially under the guise of quality when reimbursement is the motive. What I am looking for is a someone who will support the US recs based on a read on the totality of both RCT and obs data and why we opt for scopes over stool testing. For many, your site serves as a one-stop shop for non-docs. They know the high level, “get a scope,” and “Katie Couric says so,” approach to colon screening. However, beyond the unsavoriness of it all, there is real data and real reasons some smart people went the most invasive route. Your readers should hear that POV. Not so nuts, at least I dont think.

      Gary Schwitzer

      February 28, 2016 at 2:20 pm


      If you think Alan’s post missed a perspective that you can provide, the forum is open.

      Gary Schwitzer

James Allison

February 27, 2016 at 12:51 pm

I am quoted in this publication and I stand by what I have said. It disturbs me, however, that parts of the post suggest that the National Colorectal Cancer Roundtable (NCCRT) composed of the American Cancer Society (ACS) and the Centers for Disease Control (CDC) and, the U.S. Preventive Services Guidelines (USPSTF), are promoting colonoscopy over other screening tests for colorectal cancer (CRC). The last published USPSTF was 2008 though a new one is being evaluated for publication this year. The USPSTF has never labeled colonoscopy or any other screening test as the “best”, “gold standard” test and the NCCRT and ACS were the first national group to disavow the section of the 2008 ACS Multisociety Guidelines that de-emphasized the importance of fecal occult blood tests by making the following 2 statements.
“If fecal tests are used the opportunity for prevention is both limited and incidental and not the primary goal of CRC screening with these tests” “It is the strong opinion of this expert panel that colon cancer prevention should be the primary goal of CRC screening and that providers and patients should understand that noninvasive tests are less likely to prevent cancer compared with the invasive tests”
The NCCRT 80% by 2018 campaign does not recommend any test as the “gold standard” and, in fact, strongly advocates high sensitivity fecal occult blood testing like most other countries in the world including Canada. Below are a few messages the CDC and the NCCRT have been sending out
1. No CRC screening strategy has been shown to be superior but, colonoscopy is the predominant method for CRC screening in the U.S.
2. Primary-care providers are the most common source for a CRC screening recommendation. Many providers believe that colonoscopy is the best test option and do not offer other screening tests to their patients
3. The potential to increase screening rates exists if health-care providers identify the test that their patient is most likely to complete and consistently offer all recommended screening tests
The NCCRT tweets and Facebook quotes are as follows:
1. There are several ways to get screened for CRC including simple take home options. Talk to your doc about #savinglives
2. Preventing colon cancer, or finding it early, doesn’t have to be expensive. There are simple, affordable tests available. Get screened. #80by2018
3. A colonoscopy isn’t the only way to get screened for CRC. Your doctor can even give you a kit to take and use at home! Read more and talk to your doctor:
In sum the Canadian CRC guidelines provide a good guide for Canadian citizens and primary care physicians and is well thought out and guided by evidence and attention to limited healthcare resources. There are plenty of people in the U.S. who still think colonoscopy is the “best”, “gold standard” screening test but, “the times they are a changing!” and credit should be given to all groups and individuals who have worked so hard to make this change happen.

Michael Potter

February 27, 2016 at 5:59 pm

As an American family physician and as co-chair of the Professional Education and Practice Subcommittee of the National Colorectal Cancer Roundtable (NCCRT), I must take strong exception to the statement that “we don’t need to be screening more”. Colorectal cancer is highly preventable and curable through appropriate screening and follow up, and a significant proportion of the eligible population in both the US and Canada has not yet been screened. I must also make the point that the NCCRT has now for many years been among the leaders in the United States endorsing fecal immunochemical testing (FIT) as an appropriate option for healthy average risk populations starting at age 50. It is our belief that we will never reach the goal of screening 80% of the eligible population in the United States without embracing the full range of screening options that are known to be effective, including both colonoscopy and FIT. Resources and values may differ in Canada, of course, and I wouldn’t want to judge the decisions of the Canadian Taskforce and their appropriateness for the Canadian population. For more facts about colorectal cancer screening in the United States and the 80% by 18 campaign, please visit

Richard Hoffman

February 28, 2016 at 3:39 pm

I appreciate Dr. Potter’s and the NCCRT’s efforts towards promoting colorectal cancer screening, particularly through fecal blood testing. However, my comment was: “we don’t need to be screening more, we need to be screening smarter.” The context was the 80% by 18 campaign. Over the past decade, an increasing proportion of colorectal cancer screening is being performed with colonoscopy. Concomitantly, primary care physicians have increasingly indicated a strong preference for screening colonoscopy, though often erroneously assuming that it has the most convincing level of evidence. My concern is that targeting higher numbers for screening will lead primary care physicians to unduly promote colonoscopy. Unfortunately, colonoscopy is a relatively scarce resource, particularly in rural and underserved areas, and demand could exceed supply. Insisting on colonoscopy could also dissuade people who prefer a less invasive option from getting screened. I believe that dedicating colonoscopy for screening high-risk patients and performing surveillance of patients with previous colorectal neoplasia is the most valuable use of this resource. I strongly support reducing the burdens of colorectal cancer–by judiciously using fecal blood tests, flexible sigmoidoscopy, and colonoscopy.

As a general internist who encourages colorectal cancer screening—and many other evidence-based preventive services–I also recognize that many diseases are not highly preventable or curable. Randomized trials of fecal blood tests and flexible sigmoidoscopy suggest that we can reduce the incidence of colorectal cancer by about 15% to 20% and mortality by 20% to 30%. However, the number needed to screen to prevent a single colon cancer death over 10 years is about 1,000. I think we need to keep in mind the cautionary comments of Dr. Otis Brawley, the Chief Medical Officer of the American Cancer Society. He “admitt[ed]…that American medicine has overpromised when it comes to screening.”

    Michael Potter

    February 28, 2016 at 6:40 pm

    I reiterate that NCCRT endorses FIT and colonoscopy among the options for similarly effective colorectal cancer screening strategies in the United States. We agree that colonoscopy has been the most used screening strategy here in the last decade, and that it is popular among both clinicians and patients. We also agree that FIT is very much underused here. In fact, the CDC, ACS, and NCCRT and legions of researchers, public health practitioners, and advocates (including myself and others such as Dr. Allison, who is involved with NCCRT and represented on this post) have put significant energies into developing primary care and public health strategies to increase the use of FIT in the United States. It’s our belief that in the United States, high screening rates will be best achieved and sustained not by discouraging colonoscopy, but rather by providing patients with a variety of evidence-based options for screening, including FIT, that they find acceptable and will complete. Increasing the use of FIT in the US is one of the most important parts of the 80 by 18 campaign. If Canada finds a different strategy to be more effective in reducing the burden of colorectal cancer, I’ll be among the first to applaud. Once again, I direct you and other readers to for accurate information about the position of NCCRT. Who knows, you might even find resources there that we have developed could be useful in your efforts to expand the use of FIT in Canada.

Blake Cooper

February 29, 2016 at 1:38 pm

As an “end user,” (i.e., non-medical professional), I really appreciate this article. I have been pushed by numerous professionals to only consider colonoscopy as my only means for avoiding/detecting colon cancer. Thus far, I insist on the FIT, but maybe later, Cologuard.
Medpage recently had an article on about how complications from colonoscopies are (or aren’t) reported:

Tim Church

February 29, 2016 at 2:08 pm

The evidence for FOBT and sigmoidoscopy are very strong. The evidence for colonoscopy rests on observational studies, which are almost impossible to conduct in an unbiased fashion for screening outcomes. I’ve even authored a couple of papers proving the impossibility of doing unbiased observational screening studies.

That said, colonoscopy screening should provide as great or greater mortality and incidence reduction as the other methods, but how much better and at what morbidity cost is the question. The CONFIRM trial is being conducted by the VA right now to determine the answers to these questions.

Jodie Dvorkin

March 1, 2016 at 10:01 am

Thank you for this article. However, I do agree with Bradley Flansbaum that it was unbalanced. A voice from USPSTF would have been helpful. I think it is unfair to assume that all of your readers are inundated with the pro-colonoscopy bias. Many probably are, but every report should be fair and balanced, rather than assuming your readers got information from elsewhere. In your opinion the message for colonoscopy is loud, but that is your opinion.

Linda V Vincent

March 1, 2016 at 11:39 am

I am 75 years old, a breast cancer survivor of 19 years, and a CLIA California licensed laboratory tech. I also have a heart condition, paroxysmal atrial fibrillation. Sums up my challenging doctor’s scheduling me for another colonoscopy this year. My 1965 colonoscopy was negative. I questioned the colonoscopy: I know about the reliability and cost of the guaiac fecal occult blood test (much cheaper than colonoscopies), I don’t like to burden our health care system with an unnecessary procedure expenses, and with atrial fib. I can
trigger an episode from the anesthesia. lv

William peters

March 5, 2016 at 2:43 pm

A.misleading article I work for kaiser ashamed u quoted on of us all of us know 25 percent of lesions are missed on flex using stool guiac also a misses more in Canada it all about dollars which right now we have more and they have less and make up excuses all u need to do is have one patient not get screened and die of this disease could the screening be more focused yes when we have better noninvasive tests

    Kevin Lomangino

    March 5, 2016 at 7:05 pm


    Please clarify what is misleading in the post. The post observes that given the same evidence, Canada and the U.S. have come to differing conclusions on the value of colonoscopy. And contrary to your undocumented statement about what “all of us know,” the post correctly observes that there’s no compelling evidence that colonoscopies are better at decreasing mortality from or incidence of colorectal cancer compared with less invasive tests. What’s misleading about that? Also — punctuation, or at least a period once in a while, would be appreciated. :)

    Kevin Lomangino
    Managing Editor