Biker395 

I'm sure you've all heard this:

Men who cycling more than nine hours a week are six times more likely to develop prostate cancer, study finds | Mail Online

I'm always suspicious of studies like this ... and even more suspicious of the way the media reports it.

I read from another source (https://www.buzzfeed.com/kellyoakes/r...rostate-cancer) that the actual numbers were:

So a little math sez that:

0.6% of the men who cycled under 3.75 hours a week developed prostate cancer
3.4% of the men who cycled over 8.5 hours a week developed prostate cancer (no word on those in between, apparently)

This source implies that the risk of those 40-59 is 1/38 or 2.63 percent.

Prostate Cancer Risk Factors - Prostate Cancer Foundation (PCF)

So that would mean that instead of asking why so many 50+ men who cycle more than 8.5 hours a week develop prostate cancer, we should be asking why did the study have only 3/511 that did not.

Then again, this other source seems to imply that the incidence rate of prostate cancer among English men is much lower in the general population that are 55-59 ... 166/100,000, or 0.16%:

Prostate cancer incidence statistics : Cancer Research UK

Other sources say that your risk is much lower in rural China, but higher at higher latitudes in the US (perhaps less vitamin D causing increased incidence of cancer generally). Then again, other studies of men who took megadoses of vitamins showed an increase in prostate cancer risk.

So confused. Help Dudelsack!

I think I'll conjugate on this over a bike ride.

Northwestrider

There is no link between cycling and cancer other than it "may" lessen it. I have talked to several urologists about this. Exercise and low sugar intake are key to avoiding most physical problems.

RideMyWheel

My doc filled me up with all the statistics about vitamin D deficiency, and cancer was #1 on his list. He got the memo about northern latitudes. As long as we're eating a well-balanced diet, taking a moderate dosage of the vitamins we need, and getting plenty of sun, we should be fine.

The other thing he told me was to stay away from potatoes, wheat, refined sugar, white rice, and milk. He didn't say it in so many words, but if it's white, it ain't right.

edit: I didn't follow up on how I'm supposed to keep my vitamin D up without milk, but that's what he told me. I think he was being more critical of dairy from a fat standpoint than anything else.

decotriumph 

I believe most statisticians would call that single study with such similar numbers "inconclusive."

John E

I am 100% with him regarding white flour, white rice, white sugar, and the like. I am not convinced potatoes, particularly if eaten with the skin, are a problem, nor is whole wheat, unless one is gluten-sensitive.

There is growing evidence regarding Vitamin D deficiency and its link to all sorts of diseases, including cancer. I walk a fine line between the polar threats of skin cancer and Vitamin D deficiency, so I take a Vitamin D supplement.

For years I thought milk fat was the problem, so I ate nonfat plain yogurt, while reducing my cheese intake. However, my wife has read that the milk protein itself is implicated in prostate cancer, so I have cut back on the yogurt, as well.

RideMyWheel

His problem with potatoes had to do with my triglycerides. Once I understood the science, I didn't object. I don't miss French fries or potato chips. I do miss loaded baked potatoes, but I was only eating a half-dozen of those per year. Sweet potatoes are apparently exempt from this prohibition, but I wasn't abusing them, either.

My doc joined the anti-gluten crowd. He recommended two books, Wheat Belly and Grain Brain. I'm still reading and pondering. Haven't formed an opinion yet, but I'm being more careful.

i still drink a "baby Coke" at work every morning. Not giving that up.

rydabent

But-------------------------is it reasonable to assume that crushing pressures by small hard bicycle seats on a delicate area may not be the cause of or exacerbate the formation of prostrate cancer? The plain fact is that any pain is a message that damage is being done.

This is just another reason to ride recumbents since there is no pressure in that area.

And yes-----------I am standing by for a bunch of hate posts on this. And yes I know if you are a professional racer, you have to ride and "approved" DF bike. That is supported by the pig headed old fools of the UCI in league with the big money DF mfg.

gregf83 

Here's the article if you want to read it: https://online.liebertpub.com/doi/pdf...jomh.2014.0012

This sounds like a pretty weak study published in a not very well known journal. Basically, an on-line poll advertised in cycling magazines.

I think I'd wait for something of higher quality before I made any adjustments to cycling time.

Biker395 

Potatoes affect triglycerides? Oy.

They are also very rich in potassium ... something hard to get in our diet and something that has a way of counteracting all of the sodium that exacerbates high blood pressure ... and heart disease.

All this stuff comes across to me as "damned if you do and damned if you don't."

And BTW ... there are a lot of things I ain't giving up until they pry my cold dead hands off of them.

gregf83 

Yes, because everyone knows pressure causes cancer. Give it a rest...

Biker395 

Thanks for the link!

Looigi

Your prostate must be located in a different place than mine.

Dudelsack 

"Journalism is the art of transforming abysmal ignorance into execrable prose". David Bentley Hart.

Politics, climatology and medicine. All total bull*****.

donheff

You can take all of this stuff with a grain of salt. I am a bit surprised that the Doc is so accepting of the books cited. I read and enjoyed them but I have read a lot of other stuff that makes me skeptical that those particular books have the story right. My triglicerides were up (137) and total cholesterol high enough that I was on statins for more than a decade. I went very low carb for 4 months and dropped 33 pounds putting me at my ideal weight. My triglicerides instantly dropped way down and my HDL way up. LDL stayed steady even though I quit the statins. After reading a ton of stuff about low carb vs low glycemic index, vs low fat... I decided to try a bit of self experimenting. After a year of low carb, I added potatoes back into the mix, added a fair amount of rice back into the mix (preferably Jasmine which has a lower glycemic index than others) but kept sugar to a minimum and continued to eat mainly whole foods. For a year my weight has held steady at my ideal 162 pounds despite the moderate amount of carbs (I am still low compared to the average American).

Coincidentally, I had labs done last week in advance of my annual physical. I was curious if my additional carbs this year would screw up the numbers but I checked online this morning and no such problem. Triglycerides remain at 58 and HDL at 93. Gonna keep eating the bacon and eggs and the hash browns with them

A lot of this stuff is individual genetics. YMMV.

zonatandem

Over 300 thousand miles of bicycling since the early 1970s.
Had prostate issue 9 years ago. Got seed implants. Doctor suggested extra radiation or chemo.
Turned the idea down. Am doing fine with my PSA readings below 1.
Cycling has nothing to do with prostate . . .
Still riding 100+ miles a week at age 81.
My actual experience beats any study!

StanSeven

But doesn't that mean trading in lycra for flannel shirts and jeans and growing a long beard?

Biker395 

Well, finally had the time to read the study. Conclusion: Purely statistical study of questionable data. The kind of thing I'd expect to be written as a prelude to a request for more $ to fund another study.

Interesting note ... there are a couple of references to someone's speculation that "dangerous chemicals" in bike saddles might be responsible for ED and testicular cancer.

Really? lol

phoebeisis

Rode a bike a lot-got prostate cancer
That is exactly what that study implies ???

Now prostate cancer is very common in older men
so it would be a better study if it indicated high mile riders were more likely to DIE from it or all causes at a younger age than similar "not riders"
Hmmm I am 3/4 x7 5 hours

fietsbob

Both happen while you are living a life. when dead neither are an issue.

John_V 

I had very aggressive prostate cancer before I started riding a bike. Several of my friends in my age group (67 y/o) have had prostate cancer at ages younger than when I was diagnosed. None of them rode bikes. I have read several articles in the Journal of the American Medical Association (JAMA) on this and while some studies may have a correlation to cycling and prostate and testicular issues, the consensus was that there was just not enough evidence to make a definite conclusion. Since prostate cancer appears in men that don't ride bicycles, I have to wonder who finances some of the studies that are floating around. Personally, I would put my marbles on medical studies not sponsored by a pharmaceutical company than I would a nutrition study.