Questioning Colonoscopy

Everybody knows that colonoscopy is the best test to screen for colorectal cancer and that colonoscopies save lives. Everybody may be wrong. Colonoscopy is increasingly viewed as the gold standard for colorectal cancer screening, but its reputation is not based on solid evidence. In reality,  it is not yet known for certain whether colonoscopy can help reduce the number of deaths from colorectal cancer. Screening with fecal occult blood testing (FOBT) and flexible sigmoidoscopy are supported by better evidence, but questions remain.  It seems our zeal for screening tests has outstripped the evidence. 

Statistics show that the life-time risk for an adult American to develop colorectal cancer (CRC) is approximately 6%. Colorectal cancer is the second leading cause of cancer deaths in the United States. In the US there are currently 146,970 new cases   and 50,630 deaths each year. Between 1973 and 1995, mortality from CRC declined by 20.5%, and incidence declined by 7.4% in the United States.  

The US Preventive Services Task Force (USPSTF) recommends screening for colorectal cancer (CRC) using fecal occult blood testing, sigmoidoscopy, or colonoscopy, in adults, beginning at age 50 years and continuing until age 75 years.  

The American Cancer Society divides the available tests into these two categories and makes these recommendations for frequency of testing:

Tests that find polyps and cancer

  • flexible sigmoidoscopy every 5 years* 
  • colonoscopy every 10 years 
  • double contrast barium enema every 5 years* 
  • CT colonography (virtual colonoscopy) every 5 years*

Tests that mainly find cancer

  • fecal occult blood test (FOBT) every year*,**
  • fecal immunochemical test (FIT) every year*,**
  • stool DNA test (sDNA), interval uncertain*

 Screening by colonoscopy seems to make more sense than other screening methods, because you can actually see the entire inside of the colon. Colon cancer is preceded by polyps and adenomas that progress to cancer. When a polyp is seen, it can be removed during the procedure. In this study, colonoscopic polypectomy resulted in a lower than expected incidence of colorectal cancer. But other studies suggest that the progression to cancer is not a steady process, and that  adenomas may regress.

There is good evidence here and here that any benefit of colonoscopy is restricted to left-sided colon cancers, with no impact on right-sided colon cancer; we don’t understand why. Some possible explanations are discussed here.  

There are pros and cons to each of the different screening tests.  Barium enemas and CT virtual colonoscopy involve significant doses of radiation. Colonoscopy only needs to be done every 10 years, but it involves an uncomfortable bowel prep, requires sedation, can cause serious complications like bowel perforation, and is unacceptable to some patients. FOBT screening is painless and harmless but has a lot of false positives and requires annual testing. Getting patients to come back every year for FOBT is problematic. Compliance and cost must be considered. Colonoscopy is expensive and there are not enough colonoscopists to screen everyone.

 Apart from all those peripheral considerations, what do we know about the bottom line: the ability of each screening method to prevent deaths from colon cancer?  According to the National Cancer Institute,  

  • Studies have shown that FOBT, when performed every 1 to 2 years in people ages 50 to 80, can help reduce the number of deaths due to colorectal cancer by 15 to 33 percent.
  • Studies suggest that regular screening with sigmoidoscopy after age 50 can help reduce the number of deaths from colorectal cancer, perhaps by as much as 50%, but the quality of evidence is not as good as for FOBT.
  • it is not yet known for certain whether colonoscopy can help reduce the number of deaths from colorectal cancer.

No randomized controlled trials have tested whether colonoscopy reduces the incidence of CRC. Support for the role of colonoscopy in CRC prevention derives from indirect evidence and observational studies.

There is an excellent review of all the pertinent studies here.  Even though studies show that screening can reduce disease-specific mortality from colorectal cancer, there is little evidence that it reduces all-cause mortality.  So as far as we know, screening probably won’t prolong your life. It seems like it should: I don’t understand why it doesn’t, and it bothers me. This certainly isn’t the message we’re getting from the media and from the medical profession.

I’m guessing that if the appropriate studies were done and the technique of colonoscopy were optimized, a reduction in colon cancer deaths would be demonstrated. I’m guessing that colonoscopy would detect more cancers and precancerous lesions than FOBT or sigmoidoscopy, but I’m wondering whether the benefits of colonoscopy would outweigh the additional cost and risks compared to other screening methods. And I’m disturbed that a reduction in all-cause mortality has not yet been clearly shown for any screening method. We need more research to help us understand these issues.

Pending better evidence, I support the current USPSTF recommendations. I think patients should be told the pros and cons and choose which screening test they prefer. I have chosen annual FOBT for myself.

Posted in: Cancer

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31 thoughts on “Questioning Colonoscopy

  1. Yogzotot says:

    Thanks again for a very informative and interesting post. I wasn’t aware of the relative strength (or lack) of evidence for colonoscopy compared to other screening methods.

    The more I am grateful that my employer (a Germany-based international utility) has decided to offer easy, annual FOBT to all of its employers and their families – for free, as part of an annual colon cancer awareness program. You simply get a kit for yourself and each of your family members, collect stool, send it to the external lab, and you get the results back within a few weeks. No easier way to get people to screen regularly.

  2. Amy Alkon says:

    Thank you for yet another wonderful post.

    I wanted to add that there are those of us who suffer negative effects from the “conscious sedation” they use in this procedure (which I haven’t had) and an endoscopy (which I had).

    It was then I learned the term “iatrogenesis,” for when medical intervention screws you up.

    I’m a skinny (post-)Jewish redhead, who gets carsick from her own driving and can drink about a glass and a half of wine before getting drunk. I’m speculating that they gave me the same dose of anesthesia that they gave all the enormous black women there. Now, maybe I’m just extraordinarily sensitive, or maybe there’s some truth to the rumor I’ve heard that redheads feel more pain.

    I ended up losing my memory for about three weeks to a month (can’t recall – heh!) and suffering cognitive diminishment for a good bit of that time, especially the first week. Luckily, as I write a research- and humor-intensive newspaper column, I’d written a backup for when my assistant went on vacation. But, very scary, I figured out the thing about the memory loss when I realized I couldn’t recall stuff like the phone number of a very good friend of mine. We’ve known each other for about 15 years, and her number wasn’t programmed into my phone because I just knew it. Well, until the “conscious sedation.” I actually had to call information. Scared the hell out of me.

  3. BillyJoe says:

    In Australia, the recommendation follows an evidence based approach and is as follows:

    – Biannual FOBT
    10% are positive and proceed to colonoscopy

    – 5 yearly colonoscopy if you have a first degree relative or two second degree relatives with a history of colon cancer.

    The FOBT kits are presently sent out to all 50, 55, and 65 year olds and the intention is to extend this to 50, 55, 60, 65, 70, and 75 year olds in the near future. But anyone can purchase a FOBT kit from the local pharmacy anytime they wish and have the result sent to them and to their GP


    Interesting aside:

    Last week, an ex-AMA president called for colonoscopy screening to replace FOBT (despite no evidence for its effectiveness).

    (This is the same ex-AMA president who, soon after leaving the pesidency, became head of an organisation that promotes the integration of “evidence-based” alternative medicine (you have to wonder what she regards as “evidence”!) with conventional medicine. Just before leaving her job at the AMA, she pushed through an amendment that allowed doctors to advertise health products. She then immediately commenced advertising alternative health products until the decision to remove that amendment was made last year.)

  4. bhumburg says:

    Is the reason why colonoscopies haven’t been demonstrated to reduce the risks of colon cancer the fact that doctors don’t have equipoise about it?

    For your readers, in order to ethically engage in a study, doctors need to be on the fence about the risk or benefit about a particular intervention. No one should engage in a trial randomizing people into those who have people spit in their open surgical wounds and those who receive standard care, because spitting in a surgical wound is pretty much assumed to be a big risk, even before you get the trial results back. Doctors would not have equipoise about spitting in wounds or not – they’re convinced a priori that it’s a bad intervention.

    Similarly, what docs are gonna agree to not refer for colonoscopy? I think finding a group with equipoise about it would be a problem.


  5. JoBenhamu says:

    Thanks for an interesting update on this issue. In Australia we currently have the National Bowel Cancer Screening Program, funded by the federal government. This program involves mail-outs of FOBT kits to people who fall into the recommended age group. This program commenced in mid-2006. Every person turning 55 and 65 years of age between then and June 2008 were offered an FOBT. Of course this means anyone falling outside those ages will likely miss out. Follow-up colonoscopy is offered after consultation with a GP and referral to a specialist. In addition we have another program run by an organisation called Rotary offering FOBT to anyone over 40 in March of every year.

    The main problem with FOBT is that it relies on catching a polyp or cancer when it is bleeding. Ultimately a more invasive procedure will be necessary to remove any polyps that are detected. Colonoscopy or sigmoidoscopy is still the only method we have for removing small polyps.

    There are some doctors who advocate colonoscopies for all people over age 50. Even if this is supported by the evidence, our healthcare system would be unable to cope with the sheer volume of work required. The work carried out in endoscopy units has become increasingly complex over the years – in larger hospitals complex interventional and therapeutic procedures are routine. Resources are stretched due to medical and nursing shortages – not unique to Australia by any means.

    Ultimately decisions need to made based on a combination of the best available evidence and the resources available to carry out the necessary investigations and treatments. In addition, education programs that reduce the stigma of bowel investigations would go a long way to increasing the public’s responsiveness to FOBT testing.

    As an aside, in response to Amy Akon’s comments, sedation doses are titrated to the individual patient. Your idea that you were given the “same dose of anesthesia that they gave all the enormous black women there” betrays an incredibly simplistic understanding of how these medications work. While being overweight can have some bearing on response to sedation, there are a multitude of factors involved including age, alcohol intake, renal and liver function, cardiac and respiratory illness, regular use of sleeping pills and so on. Amnesia is a desirable side effect of Versed, but usually does not last longer than a few hours after the procedure. In fact it is cleared from the body within an hour after administration, but people can feel a “hangover” up to a day after. According to the literature (and it is pretty extensive) there are only a few reports of amnesia lasting longer than I have described above.

    Jo Benhamu (Clinical Nurse Specialist in Endoscopy)

  6. Plonit says:

    Is someone proposing spitting in wounds as a surgical intervention? What is the proposed benefit and mechanism of action?

  7. rork says:

    Aren’t the randomized trials we really want ones that compare screening colonscopy to FOBT, sigmoidoscopy, etc? Maybe it’s unethical to add a “nothing” arm to the study, but a head-to-head with screens now in use would be helpful. I don’t know if any such studies are in progress.

    Another complaint: Docs don’t really discuss a “no sedation” option for colonoscopy. I heard “too painful” but I was skeptical, and wondered about other motives like docs prefers you “gone” or patient looses less dignity (but I leave that at the door), and the money is considerable too. I’ve vaguely read “the rate of intubation of the cecum may decrease”. Point me to more.

  8. SF Mom and Scientist says:

    Very interesting post. I have a first-degree relative who had colon cancer at a relatively young age, so this is a subject I like to understand.

    I do have two questions.

    – I couldn’t access your link to the second study. Is this the one from Canada? If so, one of the criticisms I read is that 2/3 of the procedures were performed by a primary care physician instead of a gastroenterologist. The idea is that the gastroenterologist would be much more experience, doing procedures regularly, and would be able to spot more anomalies. (Maybe this was just an assumption?)

    – I read recently that deaths from colon cancer are decreasing in the US. Is this true? I know it is only correlation to assume colonoscopy would be responsible, but I am wondering what else could be causing this.

  9. cervantes says:

    I believe your summary of the evidence is somewhat misleading. The issue is that there is no direct evidence one way or the other about the relationship between screening colonoscopy and all-cause mortality, not that an expected association is lacking. Since colonoscopy does appear to reduce the actual incidence of colon cancer — something few if any other screening procedures can claim! — there is a presumption in its favor.

    There is a good deductive case to be made that the procedure probably does reduce all-cause mortality, although obviously the effect would not be very dramatic because colon cancer is responsible for only about 1% of all deaths in the United States. Preventing actual death from colon cancer is not the only benefit of preventing it, obviously.

    I would say that we are very far from knowing the cost effectiveness of colonoscopic screening. Our Cost Effectiveness Registry pops up one study on colonoscopy, which they give a moderate quality score to, which estimates a benefit of $25,000/QALY for screening — which is pretty damn good, though not terribly convincing.

  10. BillyJoe says:


    “[In Australia] every person turning 55 and 65 years of age between then and June 2008 were offered an FOBT. Of course this means anyone falling outside those ages will likely miss out”

    At present a FOBT test is sent out to all persons turning 50, 55 and 65 years of age. But the intention is to extend this to 50, 55, 60, 65, 70, and 75 years of age.

    It is being rolled out gradually so that endoscopy services are not overwhelmed by all the positives returned by FOBT (10% of FOBTs are positive and require follow up colonoscopy)


  11. Calli Arcale says:


    Another complaint: Docs don’t really discuss a “no sedation” option for colonoscopy. I heard “too painful” but I was skeptical, and wondered about other motives like docs prefers you “gone” or patient looses less dignity (but I leave that at the door), and the money is considerable too. I’ve vaguely read “the rate of intubation of the cecum may decrease”. Point me to more.

    They don’t discuss it for endoscopy either, and that’s a less arduous procedure. I didn’t have any lingering bad effects from the sedation for my first endoscopy, but I remembered the whole damn thing. Basically, it did zip-doodle for the discomfort, and on top of that, made me sleepy, groggy, and unsafe to drive. Totally not worth it, IMHO, so when I had another endoscopy a couple of weeks ago, I made a point of declining sedation — yet I had to tell each person that I didn’t want sedation (they were fine with that; it’s just outside the normal procedure). It was . . . awkward feeling, but really no worse than with the sedation.

    I am not looking forward to the day when, decades from now, I get old enough to get referred for a screening colonoscopy. Or even a flexible sigmoidography. It’s really not fun to have a foreign body stuck several feet into an orifice, and as I have no relatives at all who have had colon cancer (closest is my grandpa, who had some benign polyps removed and is now a reasonably healthy 83-year-old apart from some orthopedic issues), I think I’d be happy with the FOBT instead. But I would like to see the science to show whether or not it is really worth doing a colonsocopy in the absence of worrisome symptoms or a positive FOBT.

  12. antipodean says:

    The general zeal for screeing always outstrips the evidence.

    When it comes to screening for bad stuff the knee jerk reaction is always a Simpsonesque “Won’t someone think of the children”

    It just seems to be a human foible.

  13. JoBenhamu says:


    The first phase of the Program went from 2006 – 2008 (screening only 55 and 65 yo and included biennial screening) and the Second Phase was from July 2008 – June 2010 (screening 50, 55 and 65 yo and biennial screening was taken out). The original intention of the program was to include biennial screening (in line with evidence-based best practice guidelines). In the 2nd phase of the program, this was removed, but screening 50 year olds was added. They do in principle support screening everyone over 50.

    At present, a single test is sent to those in the aforementioned age groups. If it returns a negative result, they are sent a notification that they have been cleared, but there is no provision for follow-up screening. You are correct that the Commonwealth Govt is working towards a program that would include the 50-75 age group but there has been no commitment past July 2010.

    So, at present this is not a screening program, it is a testing program which at present gives us a snapshot of the population who completed the test

    In reference to your figure of 10% positive FOBT’s, the figure is actually 7%.

  14. BillyJoe says:

    Okay, I thought they actually aim for 10% in order to reduce the number of false negatives to an acceptable level. Less than that and they figure their test is not sensitive enough (which happened recently, causing a recall of the tests and the sending out new tests to all those who had used the insensitive test)

  15. JoBenhamu says:


    The rate of detection declined significantly, resulting in the disovery that the kits were faulty. The buffer (which is designed to maintain haemoglobin in the sample) broke down along with any haemoglobin when exposed to high temperatures. They recommenced the program a few months ago using a different kit.

  16. gaiainc says:

    The feedback I’ve gotten from patients is that it is the prep that is the worse part of the whole process, not necessarily the endoscopy. Having had a flex sig myself, I have to agree that the prep was not fun. Then again, neither was the flatuence that I experienced afterwards. So it goes.

    Most of my patients are choosing colonoscopy as the prep is the same for it, flex sig, barium enema, or virtual CT. They don’t want to handle their own stool to do the fecal occult blood testing. If something is seen on barium enema or virtual CT, they still need to have a colonoscopy to get the thing. If all goes well, they don’t have to do another test for 10 years. That is appealing to a lot of patients. For me, I’d take the colonoscopy. However I still have another 12-13 years before I actually have to make a choice.

  17. cloudskimmer says:

    My doctor does FOBT annually and recommended colonoscopy at age 50. Is the recommendation now FOBT and no colonoscopy unless positive? This would save a lot of money if true and makes sense if there’s no difference in detection or outcomes. In the USA we seem to give too much intervention to those who can pay while letting others go without anything except emergency treatment. Another sad example of the sorry state of health care here. I’m impressed that a country would provide kits for everyone in certain age groups based on science; good on you, Australia!

  18. davidp says:

    Significant decline in all causes deaths must be hard to detect with screening for a condition that only has a lifetime risk of 6% and takes years to develop. Effective treatment of bowel cancers will also make it harder to show decline in deaths. Looking for any sign of increase in deaths in any category (especially potentially screening related) may be more useful.

    With a mother who developed bowel cancer at 50 and another first degree relative with polyps, I have 5 yearly colonoscopies.
    I notice that they are reported as detecting more cancers than sigmoidoscopy or FOBT (sigmoidoscopy detected about 45% fewer).

    For my last one, I cycled 15km (about 10 miles) in the morning before an afternoon colonoscopy and had to wait until late afternoon. The hunger pains were far worse than the prep!

  19. Davidp, I mean this in the nicest way possible… I kind of hate you a little. ;) The morning before my colonoscopy, merely getting myself to the hospital seemed like a major feat! (And let’s not even talk about the night before! :P)

    The procedure was a snap, and the anaesthetic worked exactly as it was supposed to, and the photos were lovely. But the prep was pure torture. If the evidence for its helpfulness in screening is iffy, I’d just as soon wait another five years or more before having another.

  20. BillyJoe says:

    “I have 5 yearly colonoscopies.”

    Now that’s overdoing it.
    I think 1 every 5 years is more than adequate.
    (You’re not Irish by any chance? :))

  21. Mike Callahan says:

    It seems intuitive that if you actually look at the colon as in a colonoscopy that you will notice anything abnormal. The one doing the observing might be the weak link in any study. From my own experience with colonoscopy, the doctor pulled the scope out pretty quickly and did not scrutinize anything. I was serious when I asked him if I could have a copy of the video. He said there was no copy and that was that.
    These days I consider it pretty primitive when you don’t take advantage of technology and make a copy that you can scrutinize at a later date.

  22. JoBenhamu says:

    I want to try answer or clarify some of the misconceptions people have expressed. I understand that in some cases, the information people receive prior to their procedure is inadequate, but as a rule, this is not the case. There are many factors involved, including what the patient actually remembers being told, whether the physician in question does actually give all the information the person may want, whether the sedation for the procedure is performed by an anaesthetist or by the person performing the procedure (this can influence which drugs you receive), previous experiences of said procedures, the information given by nurses involved and so on…
    There are so many facets to what goes on in a hospital that can be confusing or frightening for patients, and some of it may seem designed to exclude the patient from the process or even to hide things from them, but in my experience this is not the case. I was sitting in a cafe yesterday and overheard a group of women talking about their experiences of having an operation. Some of what they said enhanced my understanding of why the woo is winning. They were incredibly annoyed at the fact that the surgeon might view them as “a limb” or “an organ” while they are on the operating table. I understand that when you go into hospital you want to feel cared for and that your doctor is thinking about you, Jane Smith, as he is cutting into your abdomen. I for one am pleased that they aren’t. I want them to be thinking about what the best way is to dissect your tumor from your rectum in order to entirely remove your cancer and simultaneously prevent you suffering fecal incontinence.
    Rork stated: “Docs don’t really discuss a “no sedation” option for colonoscopy. I heard “too painful” but I was skeptical, and wondered about other motives like docs prefers you “gone” or patient looses less dignity (but I leave that at the door), and the money is considerable too. I’ve vaguely read “the rate of intubation of the cecum may decrease”. Point me to more.”
    A no sedation option is usually given for sigmoidoscopy. This is because the procedure only looks at approximately 15cm of the colon. As the colonoscope is pushed around the colon, air is used to inflate the bowel so that it can be visualised. This is important for both the inspection of the bowel for disease, and so that the procedure is safe. One of the risks of colonoscopy is perforation of the colon. The risk is increased if the proceduralist cannot see where the scope is going. This is unfortunately another reason why you need to take the bowel preparation. Once you get past that first portion of the bowel, in other words a full colonoscopy, the procedure steadily becomes more painful. This is due to the insufflations of air, but also to the bowel stretching and looping as the instrument is pushed forward. This can be extremely painful for some patients. Even with sedation, a colonoscopy may have to be abandoned due to the patient finding it too painful. I have known four patients in the eight years I have worked in this area, who have elected to have a colonoscopy with no sedation at all. They were also people who described themselves as having very high pain thresholds and a degree of voyeurism. In terms of the rate of caecal intubation, there is good data to support this. Again, the right side of the colon is the more difficult part to get to. Once there, it is technically difficult to get past the caecum and into the ileum (small bowel). Again, this can be quite painful. The idea that doctors want patients to be “gone” may not be because of a negative attitude to the patient, but because it may interfere with the doctor attentiveness to the technical procedure- that and the fact the fact that it is at times quite painful, and your doctor does not want you to be in pain.

    In terms of the sedation itself, some doctors do tell patients that hey won’t be aware of anything, and this is often, but not always correct. Sedation is an unpredictable thing and not everyone reacts the same way to it. We aim to make you as comfortable as possible, while still maintaining your protective reflexes and cardiorespiratory function. We don’t want you to be unconscious. We want you to be comfortable – but it’s dependent on many factors. Some people, despite al l intention, simply stay awake throughout the test, even after having a fairly large dose, while others will drift off to sleep with a tiny dose. There is a great deal of skill in managing this and ensuring the patient is both comfortable and safe.
    Mike Callihan says: “It seems intuitive that if you actually look at the colon as in a colonoscopy that you will notice anything abnormal.”
    Yes, that is correct, however doing so requires time and concentration and small polyps can easily be missed (thus the need for good bowel preparation). In terms of recording procedures, there are some units that will do so, but in Australia at least it is not seen as necessary. II don’t think that it is a useful endeavour). We take photographs of important landmarks, such as the caecum and ileum, as well as any lesions we see. There are well researched guidelines on the minimum amount of time that a doctor should spend inspecting the colon (known as the withdrawal time) and this is viewed as a gold-standard in colonoscopy. I understand that some would think it strange not to take advantage of technology, having technology available does not mean said technology is useful. A small lesion that is not seen during the procedure itself is unlikely to be seen on repeat viewing and will usually be hidden behind a fold – again another reason why good bowel preparation is important. It is far more important for the doctor to spend time inspecting each fold while withdrawing the colonoscope from the bowel, than to be able to go back and look at what they saw originally.
    Oh, and on the issue of bowel preparation, hundreds of studies have been done on the topic. I would love to see a bowel preparation on the market which does not cause the bloating, nausea and discomfort that patients currently experience. Unfortunately, at this point, we simply don’t have one which fits all the desirable criteria. I view it as a necessary evil.

  23. BillyJoe says:


    You’d think with all the advances in medicine you’d at least be able to guaratee a completely painless preparation and procedure and one hundred percent reliable results.

    Geez, I’m going back to my homoeopath, he doesn’t cause any pain or discomfort whatsoever.

    But seriously…

    I know of someone who not only had a colonoscopy without anesthetic, but a gastroscopy as well !
    (His reason? He panics at the thought of going under an anaesthetic – a loss of control as he explains it. He is also a hypochondriac which is why he had these procedures in the first place)

  24. wales says:

    Nice post Harriet. Don’t know if you’ve seen this. The Colossal Colon is a traveling “educational” show about colon cancer which features a 40-foot “hands-on and crawl-through” model of a colon. It came to our city. It was also covered on a local news show. The woman behind the show, a young colon cancer survivor named Molly, was interviewed and was filmed giving her talk to various members of the public viewing the Colossal Colon. I was dumbstruck at the amount of fear and misinformation she supplied to the viewers. It seems to be a fear campaign touring the country promoting colonoscopy. Watch out for the Colossal Colon.

  25. andronicusrex says:

    thought it was also interesting to add that there is some evidence that CT ‘virtual’ colonoscopy screening in >65 year patients has greater ‘life years added’ than conventional colonoscopy screening. This is because of incidental CT detection of important life-threatening treatable extra-colonic findings, mainly abdominal aortic aneurysm.

  26. Harriet Hall says:


    Is the “life years added” based on actual outcomes or is it an estimate from a model? Do you have a reference?

  27. Dr Aust says:

    Perky and Davidp

    We used to have a colleague some years back with a family history of early-onset colon cancer (familial adenomatous polyposis due to an APC gene mutation) who had to have three-monthly colonoscopies. I guess the alternative was prophylactic colectomy, and he didn’t want to have that until he was forced to.

  28. Ryan says:

    It is always wise to be critical of any screening test. Even though it is intuitively obvious that catching a cancer early will save lives, there are confounding issues of side effects or complications from the screening test and with cancer screening there is always the potential for the dreaded “unnecessary diagnosis”.

    In order to get an idea of the balance, we need not only proof of reduction in cancer mortality but also solid numbers regarding the risks of the procedure or test and an idea of the excessive early “cancers” and “pre-cancers”. We’ve seen this with PSA testing in dramatic fashion with the evidence overwhelmingly showing an excessive burden of over diagnosis. With PSA screening: Approximately 48 men will be diagnosed with prostate cancer that would never have caused symptoms in their lifetime for every 1 man who has his life prolonged by early detection. The treatment for prostate cancer in those 48 men shortens lifespan enough that it appears there is no overall mortality reduction with PSA screening.
    And those 48 men who underwent treatment unnecessarily believe they were saved by the PSA test and become oncologic victories and spokespersons for the benefits of PSA screening, “early detection saved my life”. So when men make the decision whether to participate in screening PSA testing they have to understand the big harm of unnecessary diagnosis and the debatable small benefit on mortality reduction.

    With screening mammography, we see similar but less dramatic results. In women age 40-50 the risk of dying of breast cancer over a decade is between 2 and 4 in 1000; screening mammography lowers the chance of dying of breast cancer 15% so that 1 woman in 1000 (some sources say 2000) will have her life saved over a decade of screening. Unfortunately 10 women will be diagnosed over that same decade of screening with a breast cancer destined never to cause symptoms in her lifetime. Those 10 women will undergo breast cancer treatment and will appear to be saved from the therapy. In reality these 10 women were destined to survive their breast cancer whether it was detected or not. These 10 women will live their lives with the label breast cancer survivor and believe that they owe their life to “early detection”. Another 10 women will be diagnosed earlier because of screening but their outcome would have be the same with later detection, which is kind of a harm when you think of the lost year(s) being “cancer free”. But the real harm is the problem of over diagnosis AKA unnecessary diagnosis AKA pseudo disease. So when women age 40-50 choose to participate in screening mammography, they have to understand the risk of unnecessary diagnosis is 10 times that of being saved by early detection. Yes mammography can save your life but the chance of that is about 1 in 1000 over a decade and the risk of harm is 10 in 1000 over that same decade; and we’ll tell you if we harm you that we saved you not because we’re assholes but because we can’t tell the difference ourselves.

    Now with colon cancer depending on your age you have around a 4 in 1000 chance of dying of colon cancer over a decade. With screening colonoscopy you have a 2 in 1000 chance of a major complication with each procedure (bleeding requiring hospitalization/transfusion/repeat scope, perforation, myocardial infarction during sedation etc) . The average person will get 2 colonoscopies over 10 years so you can see how the risks and benefits are going to be mighty close. A big unknown in the % colon cancer mortality reduction. Even if colonoscopy reduces colon cancer mortality 60%, you’re talking about saving 2-3 of those 4 folks destined to die of colon cancer and harming 4 people with the procedure itself. This doesn’t even touch on the risk of unnecessary diagnosis, such as the anecdotally large % of people diagnosed with so called pre cancerous polyps who end up getting q3-5 year colonoscopies for decades.

    The first do no harm ideal comes into play with any screening or preventive measure since we are administering these tests and interventions to a very large number of asymptomatic people. The small chance of harm can easily overwhelm the small chance of benefit AND cost society a ton of money in the process. And as the main stream media will tell you nowadays, the cost of health care relates to all cause mortality with the whole access to care deal (those population studies are uber flawed but it’s probably true that the cost of health care relates to lack of access and thus preventable deaths)

  29. rsagall says:

    In the past 12 years I’ve had three colonoscopies for various reasons. With none did I have anesthesia. My reason is why automatically submit myself to the risks, however small, of the anesthetic? I am not macho man so I had the IV inserted just in case I changed my mind mid-procedure.

    Although uncomfortable, it wasn’t untolerable. No worse than a bad case of abdominal cramps. By the time I had had enough it was time to remove the instrument. An added benefit is that I got to watch the entire procedure on the monitor. (Perhaps of more interest to me as I am a physician.)

    I don’t necessarily recommend this approach to everyone – but it’s something some people may want to consider.

    Rich Sagall, MD

  30. Dr. Sagall,

    “Anesthesia” is only rarely used for colonoscopies. More commonly minimal/moderate sedation is used (fent/midaz or small amounts of propofol). Yes, there is a continuum from awake to anesthesia with some blurry distinction between the different levels of sedation (awake->minimal->moderate->deep sedation->general anesthesia), but anesthesia should not be used without the presence of a clinician trained in airway protection (anesthesiologist or anesthetist). In my experience, most stories of “I was asleep for my colonoscopy” are from the amnestic affects of the benzodiazepines.

    And I, like you, prefer to be awake during procedures when it is an option, and with as little sedation as possible.

    Cheers to your colon health!

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