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Exercise Tied to Lower Risk for Some Types of Cancer

well.blogs.nytimes.com

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Re: Exercise Tied to Lower Risk for Some Types of Cancer

#11

Post by epistasis »

jimrandomh wrote: post #5
jimrandomh wrote: post #2

No. 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.

I haven't read the paper itself, but even if it didn't explicitly note these caveats, it would be assumed by any reader in its intended audience.

The problem is the press representation of the papers as something they're not.

These types of papers should be published, because they are necessary to decide which hypotheses to test with interventional studies.

Re: Exercise Tied to Lower Risk for Some Types of Cancer

#12

Post by WaBlueKey »

Risks are often affected by your genetic makeup, eating and exercising habits, where you live, what type of work you do, and childhood exposure to harmful materials. There are other things that influence the risk level.

Personally, staying informed and listening to my body has been my best medicine, but I'm also aware of my family history with different diseases, which helps shape my choices.

Re: Exercise Tied to Lower Risk for Some Types of Cancer

#13

Post by seizethecheese »

Results from the source study abstract[1]:

" A total of 1.44 million participants (median [range] age, 59 [19-98] years; 57% female) and 186 932 cancers were included. High vs low levels of leisure-time physical activity were associated with lower risks of 13 cancers: esophageal adenocarcinoma (HR 0.58, 95% CI 0.37-0.89), liver (HR 0.73, 95% CI 0.55-0.98), lung (HR 0.74, 95% CI 0.71-0.77), kidney (HR 0.77, 95% CI 0.70-0.85), gastric cardia (HR 0.78, 95% CI 0.64-0.95), endometrial (HR 0.79, 95% CI 0.68-0.92), myeloid leukemia (HR 0.80, 95% CI 0.70-0.92), myeloma (HR 0.83, 95% CI 0.72-0.95), colon (HR 0.84, 95% CI 0.77-0.91), head and neck (HR 0.85, 95% CI 0.78-0.93), rectal (HR 0.87, 95% CI 0.80-0.95), bladder (HR 0.87, 95% CI 0.82-0.92), and breast (HR 0.90, 95% CI 0.87-0.93). Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment. Leisure-time physical activity was associated with higher risks of malignant melanoma (HR 1.27, 95% CI 1.16-1.40) and prostate cancer (HR 1.05, 95% CI 1.03-1.08). Associations were generally similar between overweight/obese and normal-weight individuals. Smoking status modified the association for lung cancer but not other smoking-related cancers."

[1]: http://archinte.jamanetwork.com/article.aspx?articleid=25218...

Re: Exercise Tied to Lower Risk for Some Types of Cancer

#14

Post by azdle »

I don't have access to the actual paper, but my first thought on this is to wonder if they factored in the idea that people who specifically exercise are obviously interested in being healthy and may be doing other things that are "healthy" that would affect whether they get cancer or not.

I wonder if it'd be possible to get data on people who are active, but not for the reason of being healthy, things like working construction, and compare that to see if it's the activity itself or just the mentality that comes from wanting to be healthy.

Re: Exercise Tied to Lower Risk for Some Types of Cancer

#15

Post by agumonkey »

jimrandomh wrote: post #2

No. 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 can attest to that. I had weaker health a few years ago (lack of activity mainly) but I could kick a regular schedule of activity to get back on track. An accident broke my health below the self help threshold. When you're worried you can't jog, even walk, it's hard to bootstrap the exercice-health cycle again.

Re: Exercise Tied to Lower Risk for Some Types of Cancer

#16

Post by methodover »

seizethecheese wrote: post #13

Results from the source study abstract[1]: " A total of 1.44 million participants (median [range] age, 59 [19-98] years; 57% female) and 186 932 cancers were included. High vs low levels of leisure-time physical activity were associated with lower risks of 13 cancers: esophageal adenocarcinoma (HR 0.58, 95% CI 0.37-0.89), liver (HR 0.73, 95% CI 0.55-0.98), lung (HR 0.74, 95% CI 0.71-0.77), kidney (HR 0.77, 95% CI 0.7…

Phew, 186 thousand cancers included out of 1.4 million participants? I knew cancer was not entirely uncommon but... man. That's a lot of unhappy news. Feels bad to think about.

If it is true that exercising regularly reduces the risk of cancer, I wonder what the mechanism is? Exercise builds muscle mass, improves lung capacity... Why would that have anything to do with cancer?

Re: Exercise Tied to Lower Risk for Some Types of Cancer

#17

Post by damienkatz »

methodover wrote: post #16
seizethecheese wrote: post #13

Results from the source study abstract[1]: " A total of 1.44 million participants (median [range] age, 59 [19-98] years; 57% female) and 186 932 cancers were included. High vs low levels of leisure-time physical activity were associated with lower risks of 13 cancers: esophageal adenocarcinoma (HR 0.58, 95% CI 0.37-0.89), liver (HR 0.73, 95% CI 0.55-0.98), lung (HR 0.74, 95% CI 0.71-0.77), kidney (HR 0.77, 95% CI 0.7…

Phew, 186 thousand cancers included out of 1.4 million participants? I knew cancer was not entirely uncommon but... man. That's a lot of unhappy news. Feels bad to think about. If it is true that exercising regularly reduces the risk of cancer, I wonder what the mechanism is? Exercise builds muscle mass, improves lung capacity... Why would that have anything to do with cancer?

I'd guess it doesn't really prevent cancer so much as boost your immune system so it can eliminate early tumors.

Re: Exercise Tied to Lower Risk for Some Types of Cancer

#18

Post by mrfusion »

azdle wrote: post #14

I don't have access to the actual paper, but my first thought on this is to wonder if they factored in the idea that people who specifically exercise are obviously interested in being healthy and may be doing other things that are "healthy" that would affect whether they get cancer or not. I wonder if it'd be possible to get data on people who are active, but not for the reason of being healthy, things like working c…

Here's the problem with your idea though http://www.npr.org/templates/story/story.php?storyId=1779251...

It suggests people get more benefits from exercise when they expect it.

I'm curious to hear your thoughts.

Re: Exercise Tied to Lower Risk for Some Types of Cancer

#19

Post by arcanus »

jimrandomh wrote: post #4
melling wrote: post #3

Earlier quoted context omitted.

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.)

I still agree with you, he did not place enough of the blame on scientists who are unable or unwilling to properly communicate the implications of their work.

Re: Exercise Tied to Lower Risk for Some Types of Cancer

#20

Post by trhway »

methodover wrote: post #16
seizethecheese wrote: post #13

Results from the source study abstract[1]: " A total of 1.44 million participants (median [range] age, 59 [19-98] years; 57% female) and 186 932 cancers were included. High vs low levels of leisure-time physical activity were associated with lower risks of 13 cancers: esophageal adenocarcinoma (HR 0.58, 95% CI 0.37-0.89), liver (HR 0.73, 95% CI 0.55-0.98), lung (HR 0.74, 95% CI 0.71-0.77), kidney (HR 0.77, 95% CI 0.7…

Phew, 186 thousand cancers included out of 1.4 million participants? I knew cancer was not entirely uncommon but... man. That's a lot of unhappy news. Feels bad to think about. If it is true that exercising regularly reduces the risk of cancer, I wonder what the mechanism is? Exercise builds muscle mass, improves lung capacity... Why would that have anything to do with cancer?

>Phew, 186 thousand cancers included out of 1.4 million participants? I knew cancer was not entirely uncommon but... man. That's a lot of unhappy news. Feels bad to think about.

2 out of 5 will get cancer during their lifetime.

http://www.cancer.gov/about-cancer/what-is-cancer/statistics

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