Oct 29 2008

Supplement Trial For Prostate Cancer Canceled

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For all I rail against the currently inadequate regulations of supplements in the US and some other countries, this does not mean I am against true supplements as a potential medical intervention or method of health promotion. Our bodies require nutrients, and as we push human biology to its limits by trying to live as long as possible with minimal disease and degeneration, it is reasonable to hypothesize that various nutrients may help. I often check for relative deficiencies in various vitamins related to neurological health, and even prescribe vitamins when supported by the evidence.

My problem with the current state of affair is that nutrtion and supplements are being “ghettoized” by the so-called alternative medicine movement.  Poor regulations are used (in fact were created) to bypass good science and create a hayday for snake-oil peddlers.

The only bright spot is that good clinical trials involving supplements and nutrients are still being done and the mainstream standard of care is largely based upon evidence from these trials. The supplement and CAM marketplaces are blissfully disconnected from the evidence, and that’s the problem that needs to be fixed.

A large trial (35,000 men were enrolled) involving vitamin E and selenium for the prevention of prostate cancer was recently stopped because of lack of any benefit, and the small chance of risk, from the treatments.

Of more concern, slightly more users of vitamin E alone were getting prostate cancer — and slightly more selenium-only users were getting diabetes, the NCI said.

That doesn’t prove there is a risk from the supplements, the NCI stressed: Neither blip was statistically significant, meaning it could be a coincidence.

Without statistical significance it is likely that these correlations are random and not causative, but without any benefit the slight risk was not justified. Earlier smaller trials involving vitamin E and selenium for prostate cancer were positive. This was enough to justify the larger and more definitive trial, which is negative. This is a very common pattern in the medical literature (as I wrote about last week at SBM).

The results of this trial are unfortunate – I certainly would like to be able to decrease my prostate cancer risk just by taking a vitamin – but it is best to have definitive evidence. Given that we are in the midst of a health-care cost crisis, it is extremely important to avoid wasting money on ineffective treatments. Ineffective treatments may also divert attention away from effective or potentially effective treatments.

The lessons from this and other similar large and negative trials is clear: We cannot rely upon the results of preliminary small trials. They are likely to be misleading and tend to be falsely positive. And – we need better regulations of supplements so that this valuable and very expensive-to-obtain scientific evidence gets put to maximal use.

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