Tuesday, June 29, 2010

Why Doctors Must Know Math


Just for grins, let’s go along with Jane and assume that melanoma is caused by the sun.  If we go to the latest cancer statistics from the American Cancer Society (ACS), we find that 8,700 people died last year from melanoma.  We know that sun exposure and vitamin D (along with maybe the other 5-10 photoproducts we synthesize from sun exposure) help prevent breast, colon and prostate cancer.  If Jane is correct and we avoid the sun, we run less risk of being one of the 8,700 people who perish from melanoma. But what about the other side of the coin?
According to the same ACS statistics, last year 40,230 people died from breast cancer, 32,050 from prostate cancer and 51,370 from colon cancer. So, on the one hand, we have 8,700 people die of a disease that probably isn’t related to sun exposure while on the other we have 123,650 who died from cancers known to be related to lack of sun exposure.  I don’t know about you, but I’ll go with the sun exposure, “disfiguring” superficial skin cancers be damned.
Plus, we didn’t even mention the devastating disease multiple sclerosis, a disease much more common in those with little sun exposure.  There are between 250,000-350,000 new cases of MS diagnosed each year. I’ll be happy to accept the risk of a few minor cancers to significantly reduce my risk of developing MS.
The danger of too much sun is minimal – the danger of too little sun is enormous.  I know which side I come down on.  The health trade offs remind me of a corny joke I heard when I was a kid that made such an impact on me that I’ve remembered it since.  The joke (or parable) was about economic issues, but it applies to sun exposure as well.
Did you hear the one about the guy who took big steps to save his twenty dollar shoes and ripped his 50 dollar pants?
It’s just another way of saying don’t be penny-wise and pound foolish.  In terms of our current discussion, we could say, Don’t be skin-cancer-wise and colon-breast-prostate-foolish.  Which is exactly what the misguided perspective of most dermatologists would have us be. http://www.proteinpower.com/drmike/

6 comments:

  1. I'm going with regular use of sun screen on my face for vanity issues, lots of Vitamin D supplementation, and an understanding that it doesn't take a ton of time in the sun to create some good Vitamin D. Have you looked into that at all? This is also something where I think genetics can play a huge role - my memory is that people with fair skin (who likely had a bunch of genetic formation at a place in the world with limited sun and thus developed fair skin among other traits) can manufacture Vit. D very efficiently - but I may have that reversed. As usual - radical moderate approach - guard against excessive sun exposure, while recognizing the value of some.

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  2. There is a 'use it or lose it' and/or aging issue; something like 90% of the population has lost the ability to make Vit D via the skin. If you can make D with the skin, 15 minutes in the sun, 'full body' exposure, is supposed to give you more than enough, plus all the other benefits of the solar exposure.

    Sun screen on the face for vanity, as opposed to sun screen as OCD and fear of cancer, are two different issues. However, make sure you use a screen that blocks both UVA and UVB - else, you get all the bad rays, none of the good, and no way to know when you've had too much (since you won't burn).

    One of the best ways to guard against excessive exposure is to never use the sunscreen so you develop a tan over the spring that defends you in the summer. However, that's not practical for most of us. I use sunscreen when I know I'm going to get too much sun - like boating, all day on a ball field, early season football game, etc.

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  3. "something like 90% of the population has lost the ability to make Vit D via the skin."

    Is that from Dr. Holick's new book? I've never heard that.

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  4. Garry - got that from Dr. Davis's blog, http://heartscanblog.blogspot.com/2010/01/getting-vitamin-d-right.html. Thanks for checking in.

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  5. And Donna - you are right; dark skin makes it much more difficult to make enough Vit D.

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  6. That's why I think this decision has to be highly-individualized - I expect if you looked at mortality rates from skin cancer in the subset of people with fair skin, blue eyes, freckles and a tendency to have moles, it would make a lot more sense to guard against sun exposure and supplement with Vitamin D in that population. Probably no one-size-fits-all answer.

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