Exercise Tied to Lower Risk for Some Types of Cancer
well.blogs.nytimes.com
Exercise Tied to Lower Risk for Some Types of Cancer
1–10 of 55 posts
Re: Exercise Tied to Lower Risk for Some Types of Cancer
#2No. This study is confounded and provides no evidence of anything.
The problem is that people's willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can't distinguish between exercise causing reduced cancer risk, or a third variable affecting both.
Re: Exercise Tied to Lower Risk for Some Types of Cancer
#3No. This study is confounded and provides no evidence of anything. The problem is that people's willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can't distinguish between exercise causing reduced cancer risk, or a third variable affecting both.
John Oliver explains?
Re: Exercise Tied to Lower Risk for Some Types of Cancer
#4No. This study is confounded and provides no evidence of anything. The problem is that people's willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can't distinguish between exercise causing reduced cancer risk, or a third variable affecting both.
John Oliver explains? https://www.youtube.com/watch?v=0Rnq1NpHdmw
John Oliver pointed out that the media usually distorts what the studies say. He failed to flag the problem of junk science in high-prestige journals.
(Edit: I just re-watched his segment. He does talk about P-hacking and perverse incentives, which is at least a reasonable-size chunk of the problem, just not the failure mode for this particular study.)
Re: Exercise Tied to Lower Risk for Some Types of Cancer
#5No. This study is confounded and provides no evidence of anything. The problem is that people's willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can't distinguish between exercise causing reduced cancer risk, or a third variable affecting both.
I will add that this is the sort of thing that peer review theoretically ought to stop, or at least force authors to include caveats for. Unfortunately, studies with this sort of methodology make up most of the so-called studies published, so they can't really do that.
Re: Exercise Tied to Lower Risk for Some Types of Cancer
#6No. This study is confounded and provides no evidence of anything. The problem is that people's willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can't distinguish between exercise causing reduced cancer risk, or a third variable affecting both.
The same could be said of almost any study that tried to show this. It is unethical to design the study in the way you're suggesting (i.e. stop people exercising to see if they get cancer).
They did however:
> Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment.
So even for two thin people, exercise seems to have helped. I legitimately don't see how you could design a study that you'd be satisfied with.
Re: Exercise Tied to Lower Risk for Some Types of Cancer
#7No. This study is confounded and provides no evidence of anything. The problem is that people's willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can't distinguish between exercise causing reduced cancer risk, or a third variable affecting both.
The same could be said of almost any study that tried to show this. It is unethical to design the study in the way you're suggesting (i.e. stop people exercising to see if they get cancer). They did however: > Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment. So even for two thin people, exercise…
the problem is that on noisy data, that adjustment of the variables isn't really as statistically clean as maths would say.
it's the same with red meat causes cancer studies. they say they remove smoking and lack of exercise and still wave the statistical significance.
it's very questionable how they removed the influence of these variables, since meat eaters do smoke way more, and do not exercise, and care about their health less.
Re: Exercise Tied to Lower Risk for Some Types of Cancer
#8I think it's pretty obvious. I believe that it is not that exercise helps, but sedentarism is poisonous. A sedentary 40 year old looks and feels 20 years older than a 40 year old athlete.
Re: Exercise Tied to Lower Risk for Some Types of Cancer
#9No. This study is confounded and provides no evidence of anything. The problem is that people's willingness to exercise depends on their health as much as or more than their health is affected by exercise. Because this study did not involve an intervention (it just pooled a bunch of surveys), it can't distinguish between exercise causing reduced cancer risk, or a third variable affecting both.
The same could be said of almost any study that tried to show this. It is unethical to design the study in the way you're suggesting (i.e. stop people exercising to see if they get cancer). They did however: > Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment. So even for two thin people, exercise…
The correct study is one where some participants get an intervention to make them exercise more, and some are left alone. There's no ethical issue, but running such a study would be difficult and expensive.
Adjusting for BMI does not solve the problem, because there are many things besides BMI (unmeasured confounders) which affect both cancer risk and willingness to exercise.
Re: Exercise Tied to Lower Risk for Some Types of Cancer
#10Earlier quoted context omitted.
The same could be said of almost any study that tried to show this. It is unethical to design the study in the way you're suggesting (i.e. stop people exercising to see if they get cancer). They did however: > Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment. So even for two thin people, exercise…
the problem is that on noisy data, that adjustment of the variables isn't really as statistically clean as maths would say. it's the same with red meat causes cancer studies. they say they remove smoking and lack of exercise and still wave the statistical significance. it's very questionable how they removed the influence of these variables, since meat eaters do smoke way more, and do not exercise, and care about the…
Actually, I think noise is a red herring, and that worrying about noise (instead of worrying about unmeasured confounders and incorrect causal structures) is how epidemiology got into this mess in the first place.