XYZ increases/decreases prostate cancer risk?

Almost every day I find a news flash in my inbox that proclaims another dietary supplement or drug will increase or decrease the risk of prostate cancer. Today was no exception. From ASCO (my professional society) “Cancer in the News” comes these headlines:

Preliminary Findings Suggest Daily Consumption Of More Than One Alcohol Drink Raises Cancer Risk.

Heart Medication May Significantly Lower Prostate Cancer Risk

When you scroll down and look into the details or click on these links that I have included from news flash one and news flash two, you find the epidemiology of the claims in the headlines. I have no problem with epidemiologists or their statistics. However I always remind myself of the following. Statistics are set up so that things become “significant” when there is a one chance in twenty that an observation is not due to random variation. This means that if you have twenty lab tests, it is pretty likely one will be slightly outside of the “normal” range that appears on your chemistry panel.

Call me stupid (and I will definitely admit to being a math-challenged sort of person…I have taken statistics courses three times and usually fall asleep in the “normal distribution” lecture that leads off), but it seems to me that if you do 2o evaluations of the relationship of alcohol to cancer risk, one will likely show an association (preventing or causing – take your pick). Indeed, if you look at “related articles” in the BBC news article, you find this article telling you that weaker wine may lower the risk of some cancers. The thrust, however is the same – that alcohol leads to cancer and less EtOH leads to less cancer. The salient quote is “From this, scientists calculated that, in theory, a person drinking one large 250ml glass of wine a night would have a 7% lower risk of bowel cancer if they normally drank 10% strength wine rather than 14%.”

I think it comes down to practical considerations. Stay thin – ALL of my patients who are in their 80’s are thin guys. Use sunscreen. Don’t smoke. If you have advanced cancer and are going to die from it, stop taking your cholesterol medication and enjoy a steak if you want to. I can’t tell you how many times a well meaning physician has ordered a complete iron workup for anemia in one of my patients on androgen deprivation. Anemia is one of the side effects! So to these suggestions, I would add, “don’t do everything your doctor tells you.” But I would also add, “take the cancer claims from vitamins/supplements, etc. with a grain of salt” (assuming you don’t have high blood pressure that is….)

1 Comment

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One response to “XYZ increases/decreases prostate cancer risk?

  1. Bob Lederer

    Mike, So glad you said it. Great comments.
    I follow two Prostate Cancer List-serves which are replete with these kinds of stories. I delete 80-90% without ever reading them. You are doing us a great favor by clarifying when there is good science to back up the actions.

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