Gabor Szendi: Sunbathing for melanoma prevention?
Probably ten out of ten dermatologists would contraindicate even reading this article, not to mention considering its implications. But now, that you already started reading, why wouldn't you continue? Perhaps it will rid you of a dangerous myth that has been drummed into people's minds for decades.
Beyond doubt, the prevalence of melanoma is rapidly increasing. In the US, for instance, it doubled among women and tripled among men between 1973 and 2000. Australian women and men were affected by a 40% and 88% increase respectively from 1983 to 1999. In Sweden melanoma became almost two times more common within 20 years in the general population. Reading this, dermatologists would nod their heads and say, "See, folks, the sun is not something to play around with." However, it is thought-provoking to read in the research that in Europe melanoma is most prevalent in the North, whereas it is three time less common in Mediterranean countries 17.
The farther south we go, the less melanoma we will see. If sunbathing is harmful, one would expect just the opposite to be true, wouldn't they?
That's why some researchers claimed that not the incidence of melanoma rather the number of melanoma diagnosis rises 20, 21
In his 2007 study Anthony J. Yun pointed out that while in the past 30 years people have been frightened away from sunbathing by public health campaigns, melanoma death rates have tripled in the meantime. "Is it possible that declining sun exposure levels and greater irregularity in the patterns of sun exposure related to recent behavioural modifications may contribute to the development of skin cancer?" speculated Yun 1. My answer to Yun is that this very much seems to be the case.
The authors of a 1997 review summarizing the results of 35 studies about the connection between melanoma and sun exposure concluded that people with a frequent, occupational exposure to sunlight have a significantly lower risk of melanoma as compared to the average population. Conversely, occasional sun exposure was associated with a 1.7 times higher melanoma risk. The greatest-two times higher-risk was observed among those having experienced severe sunburn multiple times during their life 2. A 2005 meta-analysis of a total of 57 studies also found that chronic, occupational sun exposure has a protective effect against melanoma, whereas irregular sunbathing and especially sunburn increases its risk 3. Therefore, it is clear that it is not sun exposure itself that causes melanoma but may be skin damage caused by repeated sunburn. However almost every studies have didn't control skin types. The so called celtic skin type (many moles, white color, red hair) has increased melanoma risk. In a study this type has 30 times melanoma risk comparing other types 19.
In his study titled "Melanoma is not caused by sunlight," Allen J. Christophers summed things up by declaring that melanoma has nothing to do with the sun. He reviewed 14 case-control studies published from 1969 to 1990 that examined the relationship between melanoma incidence and total accumulated sun exposure. Seven of them found no connection, 5 found sun exposure to be protective against melanoma, and only 2 studies found a positive correlation between the two 4.
Marianne Berwick and her colleagues' 2005 study must have been the last straw for dermatologists by pointing out, based on the re-evaluation of 528 melanoma patients, that the amount of sun exposure after disease onset is inversely related to mortality. In order to rule out errors caused by inaccurate memories of patients, the amount of sun exposure was determined based on the condition of their skin. Those who regularly sunbathed were found to have a 60% higher survival rate than the others 5. Three years later, a study by Stefano Rosso et al. evaluating 260 subjects with melanoma concluded with similar results in regard to sun exposure beforethe diagnosis of melanoma. The researchers found that those having indulged in plenty of sunbathing during their lifetime had a 60% lower risk of death compared to subjects who had spent little time under the sun 6.
According to an Australian study analyzing 26,000 melanoma cases, melanoma that is diagnosed in summer is more benign and is associated with a greater chance of recovery than that diagnosed in the other seasons 7.
Myles Cockburn and his fellow researchers found that the bulk of evidence suggesting a causative relationship between sun exposure and melanoma occurrence comes from studies based on melanoma patients' recollection of their history of sunbathing, which inherently leads to biased results. The reason for this is that for decades, public health propaganda has been persistently warning the world about the "dangers" of sunbathing, which, on one hand, makes those with melanoma feel guilty and overestimate the time they spent under the sun, while on the other hand, makes melanoma-free people believe that the reason for them remaining healthy is their "proper" (i.e. conforming to public health advice) sunbathing habits, which results in them distorting their memories the other way 8.
I do not know about you, but I have no doubts that melanoma is not caused by sunlight, except if one gets burned by the sun.
So, the lesson is: if you are afraid of melanoma, take a sunbath! Just steer clear of sunburn. May be it's a bit risky.
How does sunbathing protect against melanoma?
Frank Apperly, an American pathologist, pointed out back in 1941 that as we go from north to south, total mortality from all types of cancer decreases 9. Four decades later, the Garland brothers revealed that colon cancer takes the lives of almost two times as many people in the northern states of the US as in the southern states 10. In 1985 Ikuko Kato et al. observed the same relationship in the case of pancreatic, stomach, rectal, ovarian, and gallbladder cancers 11. In their 1989 study conducted in the former Soviet Union, Edward D. Gorham and the Garland brothers found breast cancer to be three times more common in the north than in the south 12. Last but not least, Gary G. Schwartz's and Barbara S. Hulka's 1990 study confirmed the existence of this north-south gradient in the case of prostate cancer 13.
So what is behind this mysterious phenomenon? Of course, it is vitamin D, the miracle vitamin, which is found in almost every cell in the body, controls cell proliferation and boosts immune function. Or, to be more precise, it wouldd these if people had enough of it, which is, sadly, not the case almost throughout the year in today's Western world, thanks to the wise public health propaganda, which considers a winter coat or a ski suit the safest attire for summer as well. Nevertheless, the first astounding results of research enthused scientists.
According to a 2006 review of the research by the Garland brothers and colleagues, 25 out of 30 studies on colon cancer, 10 out of 13 studies on breast cancer, 13 out of 26 studies on prostate cancer, and 5 out of 7 studies on ovarian cancer found a protective effect of vitamin D3. The slight inconsistency in the results is due to the fact that in some of the studies vitamin D3 levels were only estimated (rather than measured) based on the subjects' statements about their sunbathing habits. As far as measurements based studies go, 7 out of 7 unequivocally confirmed that vitamin D3 deficiency is predictive of developing colon cancer later in life, that women having the lowest vitamin D3 levels have a 5 times elevated risk of breast cancer, and that inadequate vitamin D3 levels in men are associated with a 3.5-fold increase in the prevalence of prostate cancer, a 6.3 times higher percentage of which is of the invasive type 14.
So why is sunbathing protective against melanoma? Because vitamin D protects against cancer.
In the war against melanoma, the civilized world has been completely led to the wrong direction as instead of decreasing, the prevalence of melanoma has increased, and the incidence of breast, prostate, and other cancers has reached epidemic proportions. Why? Because in our feverish struggle of defence vitamin D deficiency has become a pandemic.
So, folks, go under the sun!
OK, but what sunscreen to use?
The best option would be no sunscreen at all, as you do not want protection against vitamin D synthesis-it is only sunburn that should be avoided. And this is best accomplished by letting your skin gradually get used to the sun.
Johan Westerdahl et al. came to surprising results when they compared melanoma patients living in south Sweden to controls. They found that of individuals under the age of 50, those who used sunscreen consistently had more than 3 times the risk of developing melanoma on the trunk as compared to those who never used it 15. According to the summary of an international conference on the cancer-preventing effect of sunscreens held in 2000 in Lyon, France, 8 out of the 15 reviewed studies found that the use of sunscreens can increase the risk of melanoma as much as 2.6-fold, 4 of the studies found no effect of sunscreens on melanoma incidence, and 3 found sunscreens protective against melanoma 16. (Below is another summary from vitamindwiki.com.)
Of course, if you have such light skin that going without sunscreen is not an option for you, that's fine. But beware: the majority of sunscreens only protect from UVB rays, while letting through UVA light, which has a much stronger burning effect and penetrates much deeper into the skin. (The newer sunscreens protect from UVA but not from melanomas.) Moreover, many sunscreens contain harmful or even carcinogenic substances, not to mention ingredients that, as bizarre as it sounds, break down when exposed to sunlight. In 2007, the Environmental Working Group-a US-based, independent, nonprofit environmental organization-analyzed 785 over the counter sunscreen products to find that only 16% of them provide adequate protection without causing harm 17.
So, it turns out that for three decades we were completely deceived about sunbathing and melanoma.
1. Yun, AJ.: Environmental discontinuity hypothesis: Buffer dysfunctions as a source of human disease.Med Hypotheses, 2007, 68(2):434-8↩
2. Elwood, JM; Jopson, J: Melanoma and sun exposure: an overview of published studies. Int J Cancer, 1997, 73:198-203↩
3. Gandini, S; Sera, F; Cattaruzza,MS; Pasquini,P; Picconi,O; Boyle, P; Melchi, CF: Meta-analysis of risk factors for cutaneous melanoma: II. Sun exposure, Eu J Canc,2005,41(1):45-60.↩
4. Christophers, AJ: Melanoma is not caused by sunlight. Mut Res, 1998, 422(1):113-117↩
5. Berwick, M.; Armstrong, B.K.; Ben-Porat, L.; Fine, J.; Kricker, A.; Eberle, C.; Barnhill, R.: Sun exposure and mortality from melanoma. J Natl Cancer Inst. 2005, 97(3):195-9.↩
6. Rosso, S; Sera, F; Segnan,N; Zanetti, R: Sun exposure prior to diagnosis is associated with improved survival in melanoma patients: Results from a long-term follow-up study of Italian patients. Eu J Canc, 2008, 44(9):1275-1281↩
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13. Schwartz, GG.; Hulka, BS: Is vitamin D deficiency a risk factor for prostate cancer? (Hypothesis). Anticancer Res, 1990, 10:1307-1311↩
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21, Levell, NJ; Beattie CC, Shuster S, Greenberg DC:. Melanoma epidemic: A midsummer night's dream?, Br J Dermatol, 2009,161(3):630-634.↩