* Colonoscopies reduce incidence of colon cancer but apparently not death from colon cancer.
* This is probably because colon cancer therapies are good, so even if you get colon cancer your prognosis is good.
* The take-away is not that colonoscopies reduce your chances of death, but that they reduce your chances of having to suffer colon cancer and subsequent therapies. That might still be a good trade-off.
surely your risk can be further reduced by having annual colonoscopy if you are in the high risk group, e.g. with family history.
The actual study is titled "Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death" [1]
The authors conclude that "In this randomized trial, the risk of colorectal cancer at 10 years was lower among participants who were invited to undergo screening colonoscopy than among those who were assigned to no screening. "
I find it generally more useful link to the (abstract) of the original article, rather than second hand news reports. The abstracts are usually pretty accessible for a somewhat technical audience, they're not written for domain experts only. As we see in the discussions here, it's questionable whether the rephrasing from journalists really adds anything.
Like, for example, how it is called the “gold standard” because it’s a 10-year large scale randomized trial, and the doctors running the study are the ones who promoted colonoscopy as a tool to reduce cancer mortality in the first place.
The study answers a question pertaining public health policy (should we invite everyone in some age group for a colonoscopy?). It does not answer any individual health/treatment/screening question. The article's headline and content is problematic because it's easy to confuse the two, and the vast majority of readers will never get involved in public health policy (but will certainly have to make lots of individual health decisions).
"Study failed to find a reduction" _does not equal_ "There wasn't a reduction".
From the abstract: "The risk of death from colorectal cancer was 0.28% in the invited group and 0.31% in the usual-care group (risk ratio, 0.90; 95% CI, 0.64 to 1.16)"
Look at the confidence interval. This study was both consistent with a 36% reduction in deaths or a 16% increase in deaths. It's just a really wide range. All we can say about this study is that it didn't gather enough data to identify the size of the effect, not that there wasn't an effect.
This is likely because there wasn't that many people who died of colon cancer in any of the groups. This study just didn't track enough people to provide an answer.
Cancer is much more treatable, these days.
I had a friend that just underwent seven months of chemo for colorectal cancer. Looks like he'll be fine, but it was Stage IV, when it was discovered. Had a couple of surgeries, and radiation. The chemo was the worst, though. He channeled Uncle Fester, and this was a fairly robust, somewhat overweight chap.
So he would not go in the "death" column, but I guarantee that he would not be one to dismiss the seriousness of the disease (or its treatment).
This isn’t true. The secondary analysis shows a reduced death rate.
The problem with the title is that it says “Effect of Colonoscopy Screening”, not “Effect of telling people to get a colonoscopy screening”, where the primary analysis is making conclusions based on the latter.
Maybe this style of title is standard for medical journals, but the argument in this thread is based on the title priming us for what the paper is talking about, and directly leading to confusion.
Maybe you didn't read the article all the way through?
What it found was it merely inviting people to a colonoscopy did not result in less deaths from colon cancer, although it did result in fewer people being treated for it.
However, if you look at the people who actually took a colonoscopy, there was a 50% reduction in deaths from colon cancer.
That's not nothing.
But the risk of colon cancer did decrease, with a risk reduction of 18%.
Maybe they just didn't track long enough to tease out a bigger risk reduction in overall mortality, or maybe colon cancer is associated with other risk factors for mortality (like age).
Why someone would latch onto one result and not the other is probably just "blow the lid off" style reporting.
Argueing about the randomization of these numbers, and the meta-statistical aspects of that, would be funny if the subject wasn't so serious. It is also the same level of discussion you get from people like JBP, meaning it at least misses the point by a mile.
If the second-hand news report is well done, it should give you more context on the matter, and so be more useful than the "raw" abstract.
It does show quite nicely how one can lie through scientific studies and confuse people.
I’m really confused by this data. First of all, are they testing the efficacy of colonoscopy or the efficacy of inviting people to colonoscopy?
And then how is the former group’s reduction in deaths 50% and the latter group’s is about 0%?
So I'll still get my colonoscopy, thanks
When everyone who got a colonoscopy is compared to the control group 30% fewer got colon cancer 50% fewer people died of colon cancer
This data makes me think the mortality reduction benefit is bogus, but the cancer prevention benefit is real, and probably greater than 18%, maybe closer to 36-40%. If the colon cancer mortality benefit was real you'd see some reduction in the intention to treat group, and it'd be smaller than the cancer prevention effect. (The most aggressive cancers tend to be harder cancers to catch in time because they most so quickly, so most cancer screening tests will prevent more cancers than deaths)
> After 10 years, the researchers found that the participants who were invited to colonoscopy had an 18% reduction in colon cancer risk but were no less likely to die from colon cancer than those who were never invited to screening.
This seems to imply we should discount all treatments because people who choose to get treatment are more likely to get better, coincidentally by the same amount as the treatment's efficacy.
If you do medicine for profit and are allowed to advertise and market, doing more is always better.
I call that solid evidence which could potentially save millions of real lives.
We care about all-cause mortality, not cancer mortality.
https://www.respectfulinsolence.com/2022/07/27/john-ioannidi...
https://stevekirsch.substack.com/p/how-david-gorski-defends-...
Remember: you’re not being paranoid, if they are actually out to get you.
A colonoscopy is quite unpleasant; you starve for a day, and take an enema. They may sedate you before the procedure. If they don't, then the procedure is quite uncomfortable; not exactly painful, but unpleasant.
Incidentally, if they find and remove a polyp, they will plant a tattoo inside your gut to mark the spot, for the benefit of future spelunking visitors.
fast for a day, starvation is another thing and takes weeks to set in for the average westerner
I was sedated, so laxative was the hardest part of the ordeal, not the fasting or actual procedure.
I wouldn't describe it as "extremely awful". It was very uncomfortable; I'd compare it to 40 minutes of dental hygiening.
I think it's nuts that they use this procedure for screening. I'm screened for bowel cancer annually, using a fecal sample pack they send me through the post, and that I post back. No hospital visit, no treatment room, no expensive equipment, no nurses and doctors. The only reason I can think of for using colonoscopy as a screening technique is that it's costly.
I personally know 4 people who had the procedure and cancer was detected. Some further along than others. All still living.
Colonoscopy is one of the few procedures that as they screen they can also take action.
Not all cancer is the same.
Every person will have some amount of cancer as they get older. Some of the cancer will not be aggressive or disruptive enough to cause a problem before the person dies of another old-age related infirmary.
Treating cancer is not free. Treatment reduces the quality of life of the person treated. Elderly people are slower to heal, and more at risk for complications. To treat a cancer that would not cause problems in the natural lifespan of its host is an expensive mistake.
Screening technology can expand our ability to detect cancer without giving us the insight to know dangerous cancer from inconsequential cancer. When we go on to treat inconsequential cancer we've actually reduced the years of healthy life of the patient.
Sadly my oldest brother didn't catch his so quickly and the colonoscopy he had showed he was pretty far along, and ultimately the cancer spread and killed him.
I now have one every 5 years until I hit 50 then I'll move to every 2 years. The test is pretty pain and issue free, the only 'bad' part if the laxatives first, but after seeing my brother die, it is well worth the couple of hours of discomfort.
My older brothers had continued with faecal testing, but after some pushing moved to colonoscopies too, as we'd rather catch it early, than once it has taken hold.
5/1000 colonoscopy patients have complications (some fatal) which is way higher than the base rate for colon cancer.
It’s not a harmless screen like a mammogram.
A very interesting related study has become known as "The Norwegian Colorectal Study" found that early testing was a waste of money since only those with a family history of colorectal cancer or IBS symptoms or both actually got colorectal cancer before 55. For most people the polyps which are precursors to colorectal cancer do not appear before age 55. That means that the current push for aggressive testing starting at 50 is a distracting waste of time, money, and effort that should be eased back.
IIUC, there was still a reduction in colon cancer deaths, but the populations still experienced the same % of deaths from all causes.
After all the debate here in HN about the interpretation of the data and the statistics, I'm really looking forward to see a post in 15 years with the new study.
All the study really proves is that offering someone a colonoscopy isn't the same thing as giving them one.
Perhaps it was oversold, but a 20% reduction still seems significant.
> please use the original title, unless it is misleading or linkbait; don't editorialize
I'm finding myself disappointed with the application of guidelines here. The title has been changed to a completely made up headline, differing from the original, which is editorializing. It's the second time this happens in the past 24 hours - yesterday the ".. you idiot" part was removed from a blog post completely numbing the post's intention. Neither was misleading or clickbait.
EDIT: while typing this comment, the title has been changed yet again to reflect the paper's title "Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death".
The article here just looks at cancer mortality, which is not what anyone should care about.
For more recent commentary, an example is https://blogs.scientificamerican.com/cross-check/why-i-wont-...
Here some videos (may be NSFW):
https://www.youtube.com/watch?v=B1LREA1ZuUE
But there are lots more to see.
I believe what he discovered is important. Not that I believe his advice to drink ionized water (Kangen water) is scientifically sound. But that does not matter for the discovery that switching to eat rice and veggies cleans your intestine.
Don’t be so afraid of death. It’s not that bad. Really.
Source: survived an NDE. Was not my time was told, but did get a great tour of the afterlife. Don’t worry so much.
And treat strangers with kindness, they were very insistent on that. They keep score. Heaven or Hell. It’s your decision.
:-)
So, kind of like how pruning a plant does not necessarily weaken it.
Possible reasons I thought of:
- cancer cells metastasize/spread much earlier than we previously thought (https://www.statnews.com/2016/12/14/cancer-cells-spread-meta...)
- what if the presence of polyps is not all bad? i.e. maybe they keep the immune system in a tumor-responsive state, or they locally deplete nutrients that would otherwise feed other pre-cancerous cells?
The Japanese have a higher colon cancer rate, what percent die there?
Looking for death vs no-death alone as an outcome for medical diagnosis/treatment is short sighted.
This could also be true for the colonoscopy, that the more responsible/healthier people in the treatment group are more likely to get the colonoscopy and it's very possible responsibility/healthiness are driving the difference in health outcomes instead of the colonoscopy.
The control group was 50% of the population who didn't get an invitation.
The experimental group was 50% of the population who got an invitation for colonoscopy, but turned out to be subdivided into ~40% "health conscious" who actually followed up on the procedure, and ~60% who ignored it.
Presumably there's a corresponding ~40% "health conscious" component of the control group, but this experiment had no method for identifying them.
If the study only looked at that ~40% subset of the experimental group, as opposed to the entire group who received invitations, then they could no longer compare them to the control group.
I'm not sure what gold standard you are referring to (or the article or the paper - https://www.nejm.org/doi/full/10.1056/NEJMoa2208375).
Double blind studies require there to be data. An invitation doesn't speak to the effects of Colonoscopy screening at all, while simultaneously adding a confounding variable about participation. The data is about the effects of offering screenings, not the effect of those screenings, per se.
Lifelong data is the gold standard for questions about mortality and most Colonoscopy randomized trials started around 2010 (hence this very early 10-year study, which I would say is premature).
You're basicall saying "our randomization at the beginning of the trial is key to avoid biases, so we can't reassign people from the treatment group to the other group, even if they practically don't get the treatment". The reason is if you allow people to switch, your assignment is no longer random. People who avoid the treatment may have different health properties than the ones who don't.
In essence, you need your trial to be robust and large enough that a few people not getting the treatment don't matter.
Also I’m not sure if the article mentioned this, but the data seems to imply that the % of people who opted to get a colonoscopy was similar in the invited and control group.
Can you provide a source for this?
The people in the treatment group who didn’t show up must have had a 36% increase in colon cancer death (not explicitly stated in the article, but can be derived from the numbers. You need 42% × 50% + 58% × ? = 1), and (solving 42% × 70% + 58% × ? = 1) a 21% increase in colon cancer risk.
Something must have made them different from the control group. Maybe, they didn’t show up because they already were being treated for colon cancer?
https://www.technologyreview.com/2021/10/05/1036408/silicon-...
Ooh, scary dude. /s
Kids nowadays. I remember when nuclear power was a futuristic clean energy sort of ideal and when the way we figured out who was right and who was wrong on a complex topic was to let both sides openly debate and then pick who is more credible by how each is able to rally the facts in defense of their position.
Beware your society, which is doing the same thing to people like Kirsch that it did to Socrates two thousand years ago. The masses never change, apparently. All that changes is whether they're held in check or whether they're exploited by demagogues.
Lifelong correlational data is not the gold standard for questions about mortality. It's intent to treat RCTs.
I believe that's what I said. That's certainly what was used. You can't compare the group subset that didn't participate, so it's a confounding variable.
> Lifelong correlational data is not the gold standard for questions about mortality.
AFAIK it is and has been over the last century. If you aren't tracking lifelong data, your mortality data is always skewed against hidden results because you didn't want to wait. When making a paper that isn't qualified (decade long effects vs effects), it's not expected to have short time-boxed data.
The study answers a question from health policy makers: Should we invite everyone (in some age group) for a colonoscopy? Based on this study, probably not.
It does not answer questions from individuals: Should I get a colonoscopy? If you have some good reason (symptoms, doctor advice, family history), probably yes (based on other studies, not this one).
The question here is a question that the medical establishment is trying to answer: namely, "What can we, as the medical establishment do, to reduce deaths from colon cancer?" For a long time, the answer has been, "Invite people to take colonscopies". What the data here appears to show is that the action, "Invite people to take colonoscopies" doesn't actually reduce deaths from colon cancer. If the medical establishment wants to actually reduce deaths from colon cancer, they'll need to figure out something else.
I guess I do agree that the headline is likely to be counterproductive. What the data might show is that the most effective thing you as an individual can do is to be the kind of person who takes colonoscopies when invited. The unfortunate effect it might have is to make more people into the kind of people who don't take colonoscopies when invited.
Agreed. Except the most effective thing you can do as an individual is have a colonoscopy, not be the sort of person who would have one :-)
So we have two hypotheses here:
1. Having the colonoscopy is the thing that reduces deaths from colon cancer
2. Having the colonoscopy correlates to some other factor, X; and it's actually X which reduces the deaths from colon cancer.
X, for instance, could be a high willingness / ability to see the doctor when you experience early symptoms of colon cancer. That is, the more willing you are to go to the doctor when you start to have early symptoms of colon cancer, the more likely you are to survive it; and the more willing/able you are to go to the doctor when you have early symptoms of colon cancer, the more willing/able you are to have a colonoscopy.
What evidence do you have to believe that #1 is true, rather than #2?
Because if #1 is the case, the medical system should push hard on colonoscopies. But if #2 is the case, pushing colonoscopies might be a red herring. In fact, it might be counterproductive -- I've heard that colonoscopies are unpleasant; if you pressure people who don't like doctors into having a colonoscopy, and they have a terrible experience, then when they experience early symptoms of colon cancer, they may be more likely to procrastinate to avoid having another one. Rather, if #2 is the case, the medical system should try find out what can be done to make people more willing / able to get early medical care.
E.g. it's a reasonable hypothesis that patients who are more motivated to show up might also be more motivated to look up possible causes and what other steps they can take to improve their chances.
In other words, it's reasonable to expect people who comply to potentially get better at a higher rate than the efficacy of a single treatment, and teasing out how much of this effect is due to the intervention itself and how much is due to changed behaviour due to the referral is hard.
What this appears to show is that you need to get a colonoscopy to avoid colon cancer; but that you don't need to get a colonoscopy to avoid death. I'd much rather avoid colon cancer entirely than have colon cancer and survive.
But as GP pointed out, maybe you need something else to avoid death: something that is correlated with responding to the invitation to get a colonoscopy. Maybe if you're willing and able to get a colonoscopy when invited, you're willing and able to more pro-actively go to the doctor when you notice other issues that are indicative of colon cancer, allowing you to get early treatment. And conversely, maybe if you're not willing or able to get a colonoscopy when invited, you're more likely to ignore symptoms until it's too late.
Again, avoiding colon cancer in the first place is better than successfully treating it; but it does point to the fact that other interventions might be more helpful in actually preventing deaths.
Yes. This is the argument against relying on the secondary analysis in this study. Although the invited and standard care groups were randomized such that differences in putative confounders were adjusted for, the rejection of the intervention itself may have reintroduced systematic differences that reduce the reliability of the hypothesis that intention to screen for colon cancer reduces mortality. Possibly those who accepted screening colonoscopy are more attentive to other health and lifestyle practices that reduce colon cancer mortality.
Inviting patients to undergo screening colonoscopy fails to reduce rate of cancer deaths
Imagine two cages filled with identical mice. One you drop some food into, and the other you don't. They starve to death at the same rate. Surprised?
Basically in the treated group of 1103 of every 10,000 people died. And in the control group 1104 of every 10,000 people died.
So to summarize the study. Inviting someone to a colonoscopy reduces their risk of getting colon cancer by 22 basis points. Their risk of dying from colon cancer by 3 basis points, and their risk of dying of any cause by 1 basis point.
With the actual risk reduction being up to 5x this assuming it's a 20% difference in the rate of getting colonoscopies which is driving the difference.
But this makes metformin look good because it drives a much larger overall reduction in risk.
The measured intervention was not the colonoscopy, it was the invitation to screen. Only 42% of invited patients actually got a colonoscopy. This is far more persuasive to me:
> "When the investigators compared just the 42% of participants in the invited group who actually showed up for a colonoscopy to the control group, they saw about a 30% reduction in colon cancer risk and a 50% reduction in colon cancer death. “That adds to a bunch of observational study data that suggests exposing people to colonoscopy can reduce risk of developing and dying of colon cancer,” Gupta said."
As a member of the public, I don't really care about invitation to screen, but do care about the efficacy of colonoscopy. I can see invitation to screen being an important concern from a public health standpoint.
In a randomized controlled trial you either find a significant difference in your metrics, or you don't. There's no other option. In all cases where you don't find a significant difference, the problem is that the confidence interval is too wide for whatever difference seems to exist. Your argument here is a fallacy (i.e. "you just didn't do a big enough sample!") which is a variant of my personal favorite: "it would have worked if you'd done X, Y or Z!"
There's always another X, Y, or Z. The negative study is always too small for the people who believe in the thing it's testing. As a supporter of some intervention, the onus is therefore on you to prove your claim in a demonstrated scenario, not on everyone else to disprove it in all scenarios. Could it be true that colonoscopies have some significant benefit to mortality smaller than detectable by a 80,000-person RCT? Sure. But that doesn't make the headline wrong.
This study didn't find a mortality benefit. Arguing that there's some theoretical other study that might find a benefit isn't relevant.
This is a poor way of thinking about statistics. Whether you reject or not a sharp null hypothesis doesn't give you much information (See for example: https://www.gwern.net/Everything). Failing to reject in particular, can be compatible with a wide range of effects.
>In all cases where you don't find a significant difference, the problem is that the confidence interval is too wide for whatever difference seems to exist.
With enough data, there could totally have been a tight range around no effect or a small effect. This is not what we got here though.
Also note that other variables such as cancer risk came out significant, so while this study doesn't provide much inductive evidence around cancer death, we do get some deductive evidence based on the known link between cancer and death. Not to mention that cancer and cancer treatments are not fun even when they don't kill you.
What the trial showed was a small effect with a wide uncertainty on a big sample. We cannot distinguish this from zero.
Again, could the observed effect be significant with a larger trial? Sure. But that's always true for a negative result. The objection carries no information.
"Intention to treat" here means that you count everyone in the group that got an invitation to get a colonoscopy, regardless of whether or not they actually did it. Though this sounds counterintuitive, it's the "gold standard" because, if you don't do this, you leave yourself open to bias -- maybe the people who seek out colonoscopy have some symptom, family history or other reason that leads them to seek out treatment. Maybe the people who get a test get more treatment, and that treatment is harmful in the marginal case. Or just as importantly: maybe the people who don't have the time/inclination to do one would be better served by an alternative test.
Everyone (including GP) is fixating on the magnitude of the primary outcome and squabbling about whether or not colonoscopies help people. But I think the more interesting aspect of this study is that it shows that the genetic tests probably aren't inferior to the invasive, painful, time-consuming rectal exam. If that's true, it's great news!
Isn’t there just as much chance for bias if the treatment is voluntary? Maybe the people who are more likely to have health issues are less likely to treat them.
I think there is a valid question about how effective a colonoscopy is given that you get one, and a separate valid question about how effective telling people to get colonoscopies is. According to the article, this paper answer the second question strongly via “gold standard”, and the first question less strongly via secondary analysis.
Part of the reason it’s counterintuitive here is the title of the article is “effect of colonoscopy screening”, not “effect of a doctor’s invitation to have a colonoscopy screening”. The title more than suggests that we’re comparing the outcomes of actually having the screening to not having one.
> maybe the people who don’t have the time/inclination to do one would be better served by an alternative test.
I see what you’re saying - the overall effectiveness of our current system may be low because of a low rate of voluntary adoption of the colonoscopy is low, and even a lower accuracy screen could be more effective if more people opt in.
One problem with drawing a conclusion this way is it ignores the possibility for dramatic changes in either opinion or in procedure of colonoscopies. What if we had the tech to do the colonoscopy at home in private? Would that change the voluntary rate of testing dramatically?
Is it true, or not?
(In general, one would think people who got the colonoscopy got more treatment -- in this case despite having no lower a death rate -- but perhaps it does not include as much intense treatment).
That may have had something to do with him not getting a gerbillcam until he started having symptoms.
I will say his treatment wasn't fun, at all, although he'll be OK, in the long run (but chemo never leaves you the same).
For the chemo your friend likely experienced, this is especially true.
Colorectal cancer is often treated with the chemo cocktail, FOLFOX. The "OX" stands for oxaliplatin which causes nerve damage-- hearing loss (less than cisplatin, though), peripheral neuropathy, etc. The second half-life, in the body, of oxaliplatin is 535 months (44 years). And, the platinum remains in a reactive form.
I'd love to hear a professional chime in on if there are ways to speed the elimination. E.g., something like extended/extreme fasting (to free oxaliplatin from tissues) + sodium thiosulfate + blood plasma donation, or something?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2559818/
Some choice quotes from the link:
"The first elimination half-life (t1/2) for cisplatin was 5.02 months and the second 37.0 months. For oxaliplatin, these half-lifes were 1.37 and 535 months."
"...it was shown that Pt species in pUF were still present in a reactive form."
Edit: just submitted the above article:
Good for your friend to be on the way of recovering!
I'm not that surprised death rates were similar. Colonoscopies will catch pre-cancerous masses like polyps, so I can see the cancer rate being lower.
But if diagnosed with cancer, treatments are quite good for colorectal cancer, so you may not see that much of a difference in death rate on a 10 year horizon.
Changing the title to Don't Worry About Colon Cancer Death Rates, Just Continue To Do What You're Told would not have been better or more accurate.
What would be more accurate is to say the title is incomplete. Te details matter.
If the claim was "Voluntary colonoscopy screening does not reduce the risk of death over a 10 year period" it would likely be more accurate and at least calls out the "voluntary" nature of the patients examines and the limited time span of the analysis.
No study is ever perfect and everyone has limitations. You usually learn more by investigating the limitations than poking holes in the conclusions.
Is that the wrong conclusion to reach from the data?
In the case of colon cancer detected in a colonoscopy they can snip it out right there without a lot of effort, risk or lost function. Surgery on the prostate is likely to cause all sorts of problems for men.
The problem with your doctor's recommendation is that doctors recommend colonoscopy based on age, not whether you have any factors that might indicate colon cancer. I have no cancer of any kind anywhere in my family tree and they are always on me to get one.
From the article, a doctor who still believes in colonoscopy for everyone: “The first message is that screening saves lives [Ed: against this study's data] and prevents cancer. If we could have a chance to start everyone at age 45, I’d like that."
The hypothesis is that inviting people for a regular check up reduces mortality. If a lot of people don’t take up the offer because the procedure is too invasive, carries some risk, etc. then that is a very relevant variable to take into account. Vs, for example, fecal testing as mentioned in the article. It could have a lower precision, but if uptake is 100% instead of the ~40% for colonoscopy the outcomes could be much better.
This study is meant to inform the public health policy of asymptomatic screening. They tried to see if there was a benefit in offering screenings to random patients, regardless of medical history. The currently recommended screenings for asymptomatic people were adopted because meta-analyses showed they reduced cancer mortality. In the US, the US Preventive Services Task Force keeps up with new studies and revises their recommendations: https://uspreventiveservicestaskforce.org/uspstf/home.
For people with family history or other risk factors, doctors will follow different screening guidelines or just order tests whenever they think it useful.
The study's measured affect has wide errors bars indicating a larger sample size is needed. Subsequent studies could show the affect is more inline with expectations but are unlikely to show less affect.
The question as to whether this will be used to reinforce hesitancy for this procedure; we can already see it in the comment. Logic and reason are not naturally occurring traits. I predict this will be used to move more people into the control group. Going against medical advice is anecdotally meaningful.
I got colon cancer at age 35 (despite being a vegetarian, BTW), and it was first then that suspicion was raised that there could be a hereditary component - which was later confirmed by a gene test.
You should get a colonoscopy. If you are at low risk and look totally healthy after, they'll tell you that you don't need another for a good while and you'll get the benefit of not (often) getting something that you don't think you need and, as a bonus, not die of treatable cancer.
There is a money-making industry around colonoscopies and mamograms. I'm not saying to disregard medical advice in this regard as for any individual there may be good reasons to have these procedures. However you can't completely discount the financial incentives for the providers.
That's not completely true. As a Crohn's Disease sufferer, by doctor has been making me get them since I was a teenager. The indications are high for me. For "normal" people, the general wisdom (apparently based on intuition more than any quantitative analysis) has been that the risks catch up with the general population around 50.
Wrong. They recommend on both. I had no cancer in my family history but then I got colon cancer (no, I hadn't gotten a colonoscopy before--yes, I was an idiot). As a result, all my siblings' (some of whom are still in their 30s) doctors had them get colonoscopies right away. All negative, thank goodness.
Good luck with sticking your head in the sand.
That is exactly what I thought it was saying at a glance. If I skimmed the headline and moved on, instead of digging in, it might have contributed to an unconscious bias against the procedure.
> In this study, about 12,000 people in Sweden, Poland and Norway got colonoscopies. They saw a 31% reduction in their risk of colon cancer and a 50% reduction in their risk of dying from colon cancer compared with people who were not invited to get a colonoscopy.
https://www.cnn.com/2022/10/10/health/colonoscopy-study-q-an...
I can't realistically see anyone saying "No thanks, doc, I'm not going to get that colonoscopy you recommended, because I saw a headline"
This trend of saying a thing is bad because you can imagine some unbelievably stupid person misinterpreting it and misusing it is getting out of hand. At some point people are responsible for their own decisions.
Dangerous misinformation!! Censor!! I have reported the author, Angus Chen, to his employer.
Or you could just comment...
There is no answer to the question you're asking. You're seeking absolute certainty where none can be had. We only know what we know as far as we know it. Always and everywhere.
So in practice, doctors will tell you to just get the colonoscopy to save (your own) money.
https://www.cancer.org/cancer/colon-rectal-cancer/detection-...
For asymptomatic people without abnormal stool, colon cancer tests are called "screening," never "diagnostic." "Screening" is covered without cost sharing. Colonoscopy, fecal tests, etc.
>But if you have a screening test other than colonoscopy and the result is positive (abnormal), you will need to have a colonoscopy. Some insurers consider this to be a diagnostic (not screening) colonoscopy, so you may have to pay the usual deductible and co-pay.
but that variable has nothing to do with whether the procedure itself is effective or not.
Whether it’s effective on an individual basis is a related, but different, different question.
Really?
You cannot simple compare the outcomes for the people who got an invitation AND got the procedure done with the outcomes for the people who didn’t get an invitation.
You need the compare them with the people who didn’t get an invitation BUT would have got the procedure done if they had been invited.
This is not an oversight on the part of the study designers. It's called "intention to treat", and studies are done this way to get past the problem that, when you invite a bunch of people to get colonoscopies (or tell them to comply with any medical procedure), the people who go through with it are statistically very different, in all kinds of ways, from the people who don't. This makes the direct comparison of "received treatment" vs "didn't receive treatment" mostly meaningless.
You're here advocating for everyone to ignore the study and do a direct comparison of "received treatment" vs "didn't receive treatment".
Don't do this.
Who?
Sure, this is true, it's one of the reasons why results being significant or not is not very relevant. At some point you want to move towards whether the effect size is in a clinically relevant range or not.
>The objection carries no information.
Inasmuch as something like a confidence interval provides an idea of the range of the effect size, more data does carry more information. I know it's complicated to do this analysis properly with prediction intervals and such, but you have no choice if you want to be able to make good decisions with your data. A wide range estimate that doesn't allow you to make good clinical decisions is not useful.
For clinical purposes, I would even have been more confortable treating an significant but small effect in support of the "let's not test" scenario, than this wide range where the effect could be large and positive or negative on the other side and we just don't know. Significant doesn't automatically mean "do the test" and vice versa. Effect size matters! A non-significant result because of a wide interval just doesn't tell you much useful information.
No. Significance is the only thing that matters here. If you don't have a significant result, you don't have a result. Making up stories about how the results coulda-woulda-shoulda been significant if only the study was different somehow is fine for bedtime or planning the next study, but absolutely irrelevant to interpreting the clinical trial in front of you.
The CI here is not actually that wide; I was being colloquial. It's an 80,000 person trial, with 40,000 per arm. The absolute observed difference in colo-rectal mortality between the two arms was 0.03%. The per-protocol analysis (just those people who got tested) was a difference of 0.15%.
That latter figure is the best possible argument for colonoscopy, and no matter how you look at it, it's just not a big difference. Even if you ran a huge trial to get a significant result at these effect sizes, you're still talking about a difference of 15 people per 10,000 (at best) screened. That's a lot of pain and expense for very little gain.
Can you please keep it civil and avoid devolving into insults? I don't spend my time online to get treated like a fool. Now please restrain yourself from trolling even further and say "well, then don't say foolish things" because I'd flag you.
If you bothered reading the article, a paragraph reads that this particular form of screening did have an impact. Just not as significant as the community thought.
The study is about _one particular form of screening_ that might might have been oversold. Perfectly consistent with the parent observation and my own: screening is significant, curing cancer isn't as easy as avoiding it altogether.
Now, if you have something constructive to add please do so. Otherwise, please shut up and move on to some Reddit sub.
To be fair, this is not two separate problems. Anyone who's willing to run the illegal study will not care whether they can get IRB approval.
Again, not blaming Jobs for his decisions, cancer is a scary thing. Just pointing out the benefit of eering on the side of aggressiveness when it comes to treatment.
I'm not quite sure what you're asking here. If you're wondering if voluntary opt-out of colonoscopy carries risk of bias, then I'll say the following: it's an intervention that is painful, intrusive and time consuming. No reasonable person would get one absent demonstrated benefit.
Pick a thing where people are reasonably likely to do it as default behavior (eating chocolate, say), and the intervention is to abstain from doing the thing, then you'd be right to ask that question. I imagine people who voluntarily abstain from chocolate are pretty different in substantial ways than people who have to be coerced to do so. But people who don't get a colonoscopy when not pestered to do so are just...normal.
> I see what you’re saying - the overall effectiveness of our current system may be low because of a low rate of voluntary adoption of the colonoscopy is low, and even a lower accuracy screen could be more effective if more people opt in.
Not quite. I'm saying that this study did the fairest possible test for effectiveness of colonoscopies, and the effect sizes they found were on par with the genetic tests (to be clear: they didn't actually make this comparison in the RCT; I'm extrapolating from other studies.)
The evidence presented here is not that the genetic tests are a "lower accuracy screen", it's that colonoscopies are likely not better than genetic tests. That's very different.
But if we insist on measuring demonstrated benefit by factoring in participation rates, then it’s a catch-22. What if given a prior distribution of 100% opt-in, colonoscopies are effective? And you ignored my question about what if we made colonoscopies more convenient, less intrusive and time consuming, which is becoming possible with new tech. These things can change the participation rate, which in turn can flip the outcome from little demonstrated benefit to high and conclusive demonstrated benefit.
> this study did the fairest possible test for effectiveness of colonoscopies
“Fair” is a subjective term, and it depends on what question you’re asking. I agree with your statement if the question is how effective is the current system of recommending colonoscopies. It’s not the fairest test of how effective a colonoscopy screen could be if everyone shows up for the screen. Colonoscopies might be not better than genetic tests because participation rates for genetic tests are higher, as opposed to colonoscopy screening being less effective on their own.
I understand your point that the total probability is important. But so is understanding the Bayesian factors, it’s equally enlightening and important to separate and understand the effectiveness of the screen given participation, from the likelihood of participation. And you effectively cemented how important this point is by clarifying that people use knowledge of these outcomes in order to choose whether or not to participate, so framing them incorrectly can and likely does lead to unnecessary loss of life.
That is what the "per-protocol" analysis in this RCT estimates. They considered only those people who had a colonoscopy. This completely breaks randomization and is subject to investigator bias, but at least it gives you an idea of the best you could possibly do if you lived in a world where everyone was forced to get one.
And that is: a drop of 0.15% in colo-rectal death. They then attempt to extrapolate this to estimate the effect on all-cause mortality if you somehow forced everyone to get a colonoscopy, and come up with a number of 10.88% (vs. a baseline of 11.03%). So, even if you forced everyone to get a test, you'd need to test 667 people to save one life.
That's a lot of pain for very little gain.
With a sigmoidoscopy you're awake and the doctor will show you what they're looking at. I guess that's intrusive but it certainly wasn't painful.
With colonoscopy, you're under anesthesia. It was probably intrusive but since I wasn't conscious, I didn't care. There was no pain when I regained consciousness.
I'd rather do a stool sample by mail or dropping it off at the clinic if it has the same results as the colonoscopy. There's always a risk with general anesthesia.
I don't know if my case is the norm and yours is the exception. I tend to think it is. My dad missed spending time with his grandchildren and it's possible he'd still be around if he'd been examined. So get that colonoscopy.
I should also say the following: if you've got a family history of colon cancer, active symptoms, or some other reason to believe that you're at risk, studies of statistical averages don't apply to you.
https://www.cancer.org/cancer/colon-rectal-cancer/detection-...
>Soon after the ACA became law, some insurance companies considered a colonoscopy to no longer be just a ‘screening’ test if a polyp was removed during the procedure. It would then be a ‘diagnostic’ test, and would therefore be subject to co-pays and deductibles. However, the US Department of Health and Human Services has clarified that removal of a polyp is an integral part of a screening colonoscopy, and therefore patients with private insurance should not have to pay out-of-pocket for it (although this does not apply to Medicare, as discussed below).
https://www.npr.org/sections/health-shots/2022/05/31/1101861...
Which is an interesting problem, isn't it? Not inviting people might be an option, one that doesn't provide any benefits, except an number of letters not being sent. So I'd say keep the invites, because every single additional person showing up for a screening is a net win. Additional educating efforts will definetly help so, no idea how those can look like so.
We can't say that from this study.
Colonoscopy does appear to be one of the screenings that reduces mortality. (That's why this is such a surprising result and is getting a lot of attention). But that does not mean that colonoscopy screening is useful for people in their 40s. There's a lot of discussion about the benefits and risks of colonoscopy screening for people in their 50s. Colonoscopy, especially as it's practised in the US with heavy sedation, is not risk free.
As it stands, this study, while statistically very good, doesn't help anything to answer the really important questions and only confuses people by causing discussions about the study methods, then used to derive conclusions about colonoscopies (utter nonsense, but first principle thinking using supporting science /domains is really en vogue at the moment) instead of discussing the usefulness of colonoscopies in increasing survivability, early detection and decreasing probability of colon cancer.
No, it doesn’t, because the two groups of people you’re comparing aren’t actually similar, and therefore any outcome difference can’t be tied to the intervention.
The difference in outcome between those two groups may merely be that the people who go through with the colonoscopy (not fun) are also willing to go through with their doctor’s recommendations on, say, diet restrictions (also not as fun!) so are healthier and have better outcomes.
Differences with what?
Not with the counterfactual where those people didn’t get a colonoscopy! (At least as far as I can tell from the results being discussed here.)
> every single additional person showing up for a screening is a net win.
Maybe. This study doesn’t tell us much about it.
If I then split by “had a colonoscopy between 2008 and 2012, inclusive” vs “didn’t” and look at 2012 through 2021 outcomes to draw conclusions, it’s possible that that filtering makes them unlike groups (I mean, it definitionally does in at least the primary selection criteria). Given that the effort is approximately that of a SQL query, I’d be interested to know if there’s a possible signal there, which would need to be corroborated with other data sets to determine the repeatability of the correlation and then if there’s any likely causal link.
Where’s that coming from? I didn’t read the paper yet, but the article says: “A secondary analysis also offers another silver lining, Gupta said. When the investigators compared just the 42% of participants in the invited group who actually showed up for a colonoscopy to the control group, they saw about a 30% reduction in colon cancer risk and a 50% reduction in colon cancer death.“
> This completely breaks randomization and is subject to investigator bias
Yes, true. I agree with you. This is important when asking the question “how effective is recommending screenings”. But, voluntary opt-in also breaks randomization, and is subject to patient bias.
> you’d need to test 667 people to save one life. That’s a lot of pain for very little gain
Assuming that’s accurate (the article appears to disagree), I’d still be very hard-pressed to agree with this conclusion. Why is a once or twice a decade doctor’s visit spread out over many people amounting to enough pain to let someone die? How much is a life worth? Is the colonoscopy really so bad that you’re willing to risk a greater than one in a thousand chance of dying? That risk is comparable to many extreme sports.
The problem with this kind of sum up the cost and make it look large is that you didn’t do this for anything else and compare it for reference, which makes this framing prone to cognitive bias. We spend billions and have laws for keeping drivers safe, for example. You could make it look insane by adding up the billions of dollars and people-years people spent bucking and unbuckling seatbelts, but the truth is that it’s a teeny inconvenience per person for a sizeable gain in safety and reduction in the accumulated secondary costs of accidental death.
The highest plausible 10-year estimate of colon cancer prevalence from the study was 1.2%. That's 1 in 83, not 1 in 25.
Still a long way from 1:1000
The whole study is about the usefulness of regular colonoscopies as a tool to reduce mortality in the general population, and the surprise comes from the already known "usefulness of colonoscopies in increasing survivability, early detection and decreasing probability of colon cancer" not leading to a decrease in overall death rate. See the other comments in this thread about the intent-to-treat principle and why you can't compare only people who accepted the exam.
Finding a cancer earlier (in terms of staging) is probably a good thing. But finding a cancer earlier (in terms of age of the patient) possibly means they have a harder to treat, more aggressive, cancer. This might be why there's diminishing returns on population screening in younger people. Older people have easier to treat cancers and pre-cancerous polyps.
No idea if the study was done correctly or not, I am no expert in medical studies. So to rephrase it, I'd like to see a follow up study as outlined above. Reason being that the corrent one requires a lot of nuance to properly interpret (and I somehow fail to see the point of the results so far, but that ir purely on me), and we all know that technical and scientific nuance is impossible to come by in public discurs. So the risk I see is, that the current study can be seen as showing colonoscopies are pointless and needless, a piint I don't see the study making. And that is not the studies fault, it is us laypeoples and the medias fault on how we cover and consume reporting about medical studies, or scientific studies in general.