AHS13 has been and gone. Hideous trans-Pacific jetlag is now over. I am off Twitter and other social media, apart from our Whole9 South Pacific page as part of our Personal Growth September (Jamie calls it the Antisocial Media September). I will write a post on it another day to explain why we decided to surrender to our antisocial introverted selves. The main benefit of not spending wasting time scrolling through a Twitter feed is time to think and time to write. I have come to the conclusion that my 20 minute presentation on melanoma at AHS was grossly inadequate to explain my thoughts and conclusions regarding sunlight and melanoma.
I first became interested in sunlight when I was preparing an Honours project on Vitamin D and Multiple Sclerosis in medical school. I never published but I kept the research, as well as the overall feeling that sunlight is good, is necessary, and is sometimes healing. This is in contrast to what I can only describe is the state of fear when it comes to the UV radiation in Australia. This paranoia is incredibly pervasive*. Those of you who do not live Down Under might not appreciate its true extent. Otherwise sensible adults get a look of panic in their eyes when melanoma is mentioned. Children at school are not allowed outside into the sun at recess or lunch unless they wear a wide-brimmed hat. Those whose irresponsible parents dare to forget one, stay in the shade, unable to play. Every preschool and school excursion involves long sleeved rasher shirts, tubs of sunscreen applied liberally on each child and, again, hats.
*I am not talking about whether this is clinically justified as yet, merely describing the situation.
The public awareness campaigns are omnipresent. The iconic Slip!Slop!Slap! campaign launched in 1981 is widely touted as one of the most successful campaigns in the Australian history. From the SunSmart website:
Cancer Council believes its Slip! Slop! Slap! campaign has played a key role in the dramatic shift in sun protection attitudes and behaviour over the past two decades.
Wow! That’s fantastic. That campaign must have saved thousands of lives and stopped cancer in its tracks! From Melanoma Institute Australia website:
Melanoma rates have doubled in the 20 years from 1986–2006.
It is quite fascinating that most people in Australia like to talk quite expertly on the topic of melanoma. We are so well “educated” by various health campaigns that any self-respecting TV owning Aussie off the street will tell you that sunlight causes melanoma. Total strangers will point out that the visible burn on your nose from the weekend SUP adventures is practically cancer waiting to happen. And heaven forbid you mention you had blister burns in childhood. People just shake their heads and look away, as if you are not long for this world.
I like to compare that unshakeable assurance to the society’s view on saturated fat. Your Auntie Madge just KNOWS that butter on your broccoli will clog up your arteries (while she is completely safe with her low fat banana bread) and cause a heart attack. Just like she KNOWS that going out in the sun without sunscreen will result in your untimely death.
Researchers in dermatology may argue about photocarcinogenesis for another 20 years. As far as the public goes, the sun has already been condemned.
For those of us who have come to question and ultimately reject the conventional wisdom as it relates to the diet-heart hypothesis, it is almost too easy to reject this other “undisputed truth”.
It doesn’t help the cause of the sunlight fighters that they use emotional blackmail and scare tactics to “warn” the population about the dangers of that bright orb in the sky. Let me give you an example. For those of you living in Australia this will be very familiar as you have no doubt seen these “health announcements” on TV multiple times.
The self-professed aim of these campaigns is to discourage the pro-tanning attitude of the younger generation. I don’t know about you, but I feel quite uncomfortable about the imagery used in this commercial. A healthy cell transforms into a black tentacled monster which burrows its way into a blood vessel and multiplies, seeding the body with its progeny. Children will have nightmares. I realise this is a pictorial representation but this is not what happens. Hard-hitting messages are sometimes necessary but you need to be absolutely sure that your message is 100% backed up by solid evidence.
And this is where we hit a little snag.
This particular commercial seems to imply that tanning increases the risk of melanoma. Let’s examine this assertion in a little more detail.
1. Having a tan is generally associated with chronic sun exposure. Chronic (occupational) sun exposure has been repeatedly shown to be protective against melanoma (Elwood and Jopson, 1997).
2. Tanning and sunburn are two different things. The evidence on sunburn and melanoma is not foolproof but there seems to be a slightly increased risk.
3. The ability to tan is first and foremost influenced by your skin phenotype which is genetically predetermined. When it comes to melanoma, your skin phenotype is one of the recognised risk factors. In other words, those who are able to tan are at less risk than those (unfortunate redheads) whose skin seems to go from “pale blue” to “scorched red” to “ginger peel” with not a hint of a healthy glow. So the very fact that you are turning a nice chocolatey brown the minute you expose an inch of flesh may indicate that you have a favourable phenotype. But, of course, not everyone with skin type I develops melanoma either!
4. All tan is not the same. Although they look identical, skin tans induced by different UV wavelengths have different mechanisms. UVB-induced tan causes dramatic increases in melanin synthesis. In contrast, UVA has no effect on melanin content. The tan produced by UVA is due to the distribution and oxidation of pre-existing melanin precursors. (Miyamura et al (2011) The deceptive nature of UVA-tanning versus the modest protective effects of UVB-tanning on human skin, Pigment Cell Melanoma Res). Melanin = photoprotection. Hence UVA and UVB have totally different protective qualities.
Maybe to be on the safe side we should stay indoors and avoid the sun altogether. But it seems that those who work indoors and bask under the cool office lights are, in fact, at higher risk of melanoma.
Godar et al (2009) Increased UVA exposures and decreased cutaneous Vitamin D3 levels may be responsible for the increasing incidence of melanoma. Medical Hypotheses 72:434-443
“Paradoxically, although outdoor workers get much higher outdoor solar UV doses than indoor workers get, only the indoor workers’ incidence of cutaneous malignant melanoma (CMM) has been increasing at a steady exponential rate since before 1940.”
“In fact, outdoor workers have a lower incidence of CMM compared to indoor workers”
In diagnosed melanoma cases, previous exposure, intermittent or chronic, is associated with lower mortality. Which seems to make no sense at all if you subscribe fully to “sunlight causes melanoma” argument.
Rosso et al (2008) Sun exposure prior to diagnosis is associated with improved survival in melanoma patients: results from a long term follow up study of Italian patients. European Journal of Cancer 1275-1281
“Time spend on the beach during adulthood (on average 3 weeks/years for 19 years) was inversely associated with the risk of death…”
There are plenty of grey areas in the UV-melanoma story but tanning is certainly not one of them. I would love sending a public message to the organisation who sponsored the ad, requesting to show a single study linking suntan with melanoma.
Here is my new anti-Sun campaign suggestion. I think we are not far off that.