The great melanoma debate

To screen or not to screen
To screen or not to screen

In classic yuppity form, a pretty entertaining and insightful back and forth was had between hewlfaz and eeo361. The topic of discussion was sunlight exposure and melanoma risk, prompted by the article linked below, which suggests that ‘scientists have it wrong’ regarding the connection between the two.

‘Scientists Blow the Lid on Cancer and Sunscreen Myth’

hewlfaz: 

 A few thoughts:
1. Sensational headline
2. Sweden = white people
3. Mortality higher in those avoiding sun exposure; could easily correlate with more sedentary, less relaxed, obese,
4. Also, the article clearly misquotes the 2000 swedish article about sunscreen causing cancer – the abstract states that “sunscreen use, by permitting more time sunbathing, is associated with melanoma occurrence” – which is essentially saying the sun does cause melanoma.

Prehistoric humans also had more hair and darker skin than the average human today. Life expectancy probably played a role in that there wasn’t much selection pressure against skin cancers (they typically come on later in life, after reproductive peaking).

I just think trying to find all these random associations with and against cancer aren’t really getting down to the problem – it is inevitable really. Often times it can do a disservice to people by giving them conflicting information. Point being; people should 100% wear sunscreen until we have much better data; which we don’t.

eeo361:

I read a rebuttal to this article about the supposed link between sunscreen use and the development of cancer as well. I agree that the link there is tenuous (and probably ridiculous). Similarly, the facts seem to suggest that the link between sunlight and developing melanoma is equally tenuous (and quite possibly ridiculous).

I think the best part about sunscreen is in preventing burns, not in preventing melanoma.

hewlfaz:

When it comes to prevention the recommendation is to avoid sun exposure between 10-3 and to wear protective clothing; sunscreen isn’t the mainstay. I think partly why sunscreen doesn’t protect against melanoma is because UVA radiation still causes DNA damage.

The facts for sunlight directly causing melanoma ( DNA damage leading to melanoma) are as strong as facts we have for anything in medicine. There are many studies showing a clear link between the two and there aren’t many studies showing that they are not related.

eeo361:

(quote from article) “Bernard Ackerman, MD, (deceased 2008) was one of the world’s foremost authorities on the subject of skin cancer and the sun, sunscreens and melanoma skin cancer risks:
‘The link between melanoma and sun exposure (dermatology’s dogma) is unproven. There’s no conclusive evidence that sunburns lead to cancer.There is no real proof that sunscreens protect against melanoma. There’s no proof that increased exposure to the sun increases the risk of melanoma.'”

? I guess that is all I am basing my opinion on

eeo361:

http://en.wikipedia.org/wiki/A._Bernard_Ackerman

Seems legit.

eeo361:

…he wrote the seminal textbook on melanoma diagnosis

hewlfaz:

I’m saying there are links to lots of things that are unproven, just because one researcher has an opinion doesn’t mean we should disregard the recommendations held by hundreds of other as-qualified individuals.

Even if melanoma is an outlier we should still be careful because of the other skin cancers that are definitely caused by the sun (even by Ackermans admission).

I think the debate about melanoma is less about the sun and more about the need for further research. Ackerman wasn’t trying to do harm by posing an alternative theory, he was trying to cultivate a different approach to melanoma.

The rules for regular skin cancer still apply. Sun exposure should be limited. Sunscreen is probably not that good but its arguably better than nothing.

hewlfaz:

Diet, oncology and neurology (the brain) are interesting in that there is tons of research but we still don’t really understand the basics. These also happen to be great topics to argue about because you can effectively argue any side you want and have a decent case for it.

eeo361:

I also think its interesting that melanoma gets so much press. I feel like its incidence is very low, especially compared to other cancers. And a young person getting melanoma is even more rare. Where’s the love for… renal cell carcinoma? I guess the worry of melanoma directly relates to how someone might spend their day at the beach or on vacation. More commonplace cancers are less vivid in the imagination.

eeo361:

Also, is the opportunity cost of losing sun exposure to prevent rare cancers worth it? I’m assuming adequate sun exposure is important.

hewlfaz:

I think sun exposure may be overrated. And 10,000 years ago melanoma wouldn’t have been well documented, someone dying of metastatic disease could easily have been thought infection right?

What if you consider that most Northern European countries are known to be the healthiest and have some of the lowest sun exposure rates per capita?

eeo361:

(An aside:) You guys have likely become accustomed to my hasty deployment of what I’d like to call the ‘Jurassic Park Principle’ (don’t fuck with nature) especially when considering the unknown effects of behaviors that deviate markedly from our behavior in an ancestral environment. Really, its a form of the precautionary principle. We should recognize much of modern behavior is a strange experiment we’ve been conducting on ourselves and take heed accordingly. At the very least, I’m glad you don’t think it absurd to consider our evolutionary past in these discussions. Many people I talk to think the concept is from Mars.

eeo361:

Anyways, regarding sunlight: through evolutionary timescales, we’ve adapted to harness the energy of a specific subset of UV light to catalyze the synthesis of a very important steroid molecule, Vit D. It stands to reason that there are probably other sunlight adaptations that we haven’t discovered yet. So the precautionary principle here would say we ought to get some sunlight.

Now with some of the positive advances of modernity, it may actually not be that important, speculatively, as people aren’t dying from being sunlight deprived (not that we know). I think the question I posed actually is a question that lives at the margins: is inadequate exposure to sunlight worth preventing melanoma or skin cancer over? Well, the untoward effects of both scenarios are likely rare in incidence, so it might be a pick your poison situation

eeo361:

Interestingly, fair skin is theorized to be an adaptation to UV scarcity at higher latitudes. Also, it’d be interesting to get a measure of, say, Vit D levels from societies who spend all day outside. Finally, the odds of me venturing out of my air conditioned home are zero.

hewlfaz:

I think we are converging on the same point egg. By saying melanoma may be associated with sunlight we are potentially limiting sunlight to many people who could benefit from vitamin D, mood enhancement, and potential happiness. At the same time, melanoma is such a bad disease (it really is) that the ability to prevent 1 or 2 cases here and there may be worth it. Once we know more about the link with sunlight we can adjust recommendations.

However, people should be responsible with sunlight and even more responsible with having their moles checked and having good regular check ups – this actually the area where most of the good can be done. There is no reason why one can’t have sunlight, supplement with vitamin D when needed (winter), and have prudent surveillance of skin lesions when needed.

Fin.

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