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Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

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Re: Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

#21

Post by kmonsen »

rob74 wrote: post #18
JamesBarney wrote: post #8

Earlier quoted context omitted.

The gold standard is the invitation. Imagine a study where you try to get one group of people to exercise, and you leave the other alone as a control group. Imagine you find that everyone who actually does the exercise lives much longer. This might be due to the exercise, or it could be that exercise doesn't work but healthier more responsible people followed through with the exercise. And the being healthier and mor…

Or it could be that the people that are not necessarily healthier, but have a history of cancer in their family, may be more likely to respond to a colonoscopy invitation? One way or the other, this is all just guesswork...

I feel this is a really reasonable take. This study doesn’t say anything bad about colonoscopy, it says that it is possible the effects are not only due to the colonoscopy so it is probably between 0 and claimed effect effective. Can’t really say where in the range from the study.

Re: Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

#22

Post by divbzero »

pbourke wrote: post #15
JamesBarney wrote: post #8

Earlier quoted context omitted.

The gold standard is the invitation. Imagine a study where you try to get one group of people to exercise, and you leave the other alone as a control group. Imagine you find that everyone who actually does the exercise lives much longer. This might be due to the exercise, or it could be that exercise doesn't work but healthier more responsible people followed through with the exercise. And the being healthier and mor…

In this case they are examining colon cancer and deaths from it, and the colonoscopy is a diagnostic test for colon cancer. I feel that the results are being presented to the public in a very misleading way. People will read this headline and conclude that they don’t need to get a colonoscopy which I don’t think follows from this study at all.

I agree. Even if intention-to-treat is the gold standard endpoint for trials, a more accurate and nuanced headline for the general public would be:

Inviting patients to undergo screening colonoscopy fails to reduce rate of cancer deaths

Re: Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

#23

Post by elcomet »

hef19898 wrote: post #10
hannob wrote: post #4

Earlier quoted context omitted.

They're doing an intention to treat analysis, which can be a bit confusing, but statistically makes sense and is the gold standard for clinical trials. 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, you…

Then the title is wrong, since colonoscopies actually do increase survival rates (everything would have surprised me a lot as someone who was saved by one), but rather that invitations for colonoscopies don't work. No idea why, but maybe people willing to do one go anyway while those unwilling are very unlikely to follow an invitation. Either way, the title is wrong, misleading and very clickbaity.

What you're saying is not totally correct. If you look only at patients that did get a colonoscopy, you cannot be sure that it is the colonoscopy that helps, or another variable (those people might monitor their health closer). Your assignment is not random any more so you cannot make any causal statement.

Re: Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

#24

Post by calderwoodra »

> The risk of death from any cause was 11.03% in the invited group and 11.04% in the usual-care group

IIUC, there was still a reduction in colon cancer deaths, but the populations still experienced the same % of deaths from all causes.

https://www.nejm.org/doi/full/10.1056/NEJMoa2208375

Re: Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

#27

Post by em500 »

Several posters have criticized the title of the news article "In gold-standard trial, colonoscopy fails to reduce rate of cancer deaths".

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.

[1] https://www.nejm.org/doi/full/10.1056/NEJMoa2208375

Re: Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

#28

Post by hef19898 »

em500 wrote: post #27

Several posters have criticized the title of the news article "In gold-standard trial, colonoscopy fails to reduce rate of cancer deaths". 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 colono…

That makes so much more sense and would lead to a much better discussion. Any chance the title and linked site can be changed?

It does show quite nicely how one can lie through scientific studies and confuse people.

Re: Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

#29

Post by ricardobeat »

em500 wrote: post #27

Several posters have criticized the title of the news article "In gold-standard trial, colonoscopy fails to reduce rate of cancer deaths". 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 colono…

There is nothing wrong with the title. The study failed to find a reduction in death rate despite lowering the incidence of cancer, and that is the center of the piece. It goes into detail of why this is surprising. The study authors were interviewed and agreed. The reporting actually adds a lot of context that you would never get from a link to a random study.

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.

Re: Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death

#30

Post by gwd »

pbourke wrote: post #15
JamesBarney wrote: post #8

Earlier quoted context omitted.

The gold standard is the invitation. Imagine a study where you try to get one group of people to exercise, and you leave the other alone as a control group. Imagine you find that everyone who actually does the exercise lives much longer. This might be due to the exercise, or it could be that exercise doesn't work but healthier more responsible people followed through with the exercise. And the being healthier and mor…

In this case they are examining colon cancer and deaths from it, and the colonoscopy is a diagnostic test for colon cancer. I feel that the results are being presented to the public in a very misleading way. People will read this headline and conclude that they don’t need to get a colonoscopy which I don’t think follows from this study at all.

> People will read this headline and conclude that they don’t need to get a colonoscopy which I don’t think follows from this study at all.

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.

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