New (preliminary) evidence that cyclists can have a higher incidence of prostate cancer - 3 to 6 times higher! That's a lot!

Road Bike Rider

Is Prostate Cancer More Prevalent Among Serious 50+ Riders?
Question:

The June 2014 issue of Journal of Men's Health published a study that riders 50 and over logging 4 to 8.5 hours or more per week were three times more likely to develop prostate cancer than those riders logging four hours or less per week. Are you aware of this study? Can you comment? Thanks. –

Robert B.
Dr. Richard Ellin Replies:

I was able to get a copy of the article and read it. The article did, in fact, find an association between weekly cycling time and the odds of having prostate cancer. There are many potential issues with the study, which the authors readily admit. Nevertheless, here is what they found.

The study was done by surveying 5,282 male cyclists in the UK in 2012-13. They relied on people's self-reporting of cycling time and prostate cancer. (They also looked at erectile dysfunction and infertility, but I won't comment on that here).

Based on these self-reports, the authors found that those who cycled 3.75-8.5 hours per week had a roughly 3 times higher prevalence of prostate cancer compared with those who cycled less than 3.75 hour per week, and those who cycled more than 8.5 hours per week had a 6 times higher prevalence, controlling for age, smoking status, body mass index, presence or absence of hypertension, alcohol intake, and other physical activities.

The authors stress that this study merely shows a relationship between duration of cycling and prevalence of prostate cancer. It does not imply or indicate causality.

They postulate several mechanisms by which cycling might increase the risk, but clearly state that more investigation needs to be done to both confirm the association, and investigate the possible causes.

They readily admit that it's possible being a cyclist simply means that one is more likely to have their prostate cancer diagnosed, for any number of reasons.

So it does raise some concern. However, I typically cycle about 4 hours most weeks, and don't plan to cut back, but it does give one pause.

Richard Ellin, MD, FACP, is a board-certified specialist in Internal Medicine who practices in Alpharetta, Georgia. He received his medical degree and completed residency at Emory University, and has been in practice with Kaiser Permanente for 26 years. He is also an avid cyclist.