Sun safety, sunscreen and skin cancer: sorting fact from fiction

Prof Adele Green:
Thanks, Clare. That’s fine.

Clare Blake:
Not all melanomas are from sun exposure, are they?

Prof Adele Green:
Oh, no. And not all skin cancers are from sun exposure either. Let’s start with the skin cancers because they’re much more common. And by skin cancers, I’m talking about basal cell and squamous cell carcinoma that you’ve mentioned. So they’re coming from the top layer of the skin that we see every day. And then the melanomas you mentioned are much more serious and rarer, and they come from the cells that give us our tan. And they’re called pigment cells. Starting with the skin cancers, which are the very big group, some of those can be caused by constant heat, by irritation from chemicals, but the vast number are caused, indeed, by sun exposure. And it’s really the same for melanoma. There are some genetic predispositions. By and large, it is sun exposure that is driving that, and that’s why we need protection and things like sunscreen to try and prevent this. But I imagine we’ll be talking about that.

Clare Blake:
We will. Our knowledge of Australians and skin cancer really changed as a result of your Nambour study. What did you look at?

Prof Adele Green: 
Funnily enough, we don’t really know how common skin cancer really is in this country. We know that the Indigenous people don’t get very many, and we know that the fair-skinned population get a lot. We also know, Clare, that it’s costing our government huge amounts, but we actually just don’t know the actual incidence of it. It was as simple as that is why we started off the study in a typical Queensland township. They weren’t flying in and out and it wasn’t a holiday resort. And yet we knew we had a balance of typical Australian people and we could count how many skin cancers they had. From there, we investigated, of course, the risk factors for skin cancers. And again, I’m talking about those three big skin cancer groups that I told you about: basal cell carcinoma, called BCC; SCC, squamous cell carcinoma; or melanoma. And we wanted to count those. And then we wanted to see the risk factors. And then one thing led to another and we found what people were really asking was about sunscreen, because at that stage we didn’t really know whether it was a preventive for long-term skin cancer. So that was really the evolution of the Nambour study. So at 20 years, thanks to the huge dedication, firstly, of the community who were randomly selected from the electoral roll, as it happens, way back in 1986 and they stayed with us right till 2007, [and] the most marvelous team of researchers here at QIMR.

Clare Blake:
And very close to your heart, as a girl from the tropical climes.

Prof Adele Green:
Indeed. Yes, as Queenslanders, I think if Queensland can’t deliver the answer, then there’d be something wrong.

Clare Blake:
And what did you find?

Prof Adele Green:
Well, the first thing we found was how common it was. Firstly, we found that when dermatologists looked at people’s skins, up to about five per cent of people had skin cancers actively on their skins. And we also found, because we looked at photo-ageing, which means premature aging due to sun exposure of the skin, we also found that was extremely high. That was probably one of the most shocking things that even in young people – by young people I mean adults, the youngest people we looked at was 20 to 29 – about 40 per cent of the men there had severely sun damaged photo-aged skin. Premature ageing of the skin is the very first risk factor for skin cancer. So we’re on our way, even in our 20s, to being at risk for skin cancer. That was our first mission: How common is it? Very common. What was the incidence rate? Up to one to two per cent of people per year per 100 people develop a skin cancer, which is huge rates compared with most other cancers. Of course, they’re the commonest cancers in the world. So now let’s come to the risk factors. The major ones we found had been known by others, but we could be quite exact about the real factors that we have personally that might increase our risk – fair skin being right at the top. I mentioned right at the beginning, Aboriginal and Torres Strait Islander people rarely get skin cancer because they’re protected by their dark colored skin, by their heavily pigmentated skin. We, as white people, we are very prone. So white ethnic group, and then fair-skinned within the white ethnic group, are one of the key risk factors. Age, because the older you are, while certainly you’re more at risk for any cancer as you get older, it also is a measure of the accumulation or the accumulated effect of things in the environment that might drive the cancer. Of course, here we’re talking mostly about sun exposure. And to break that down, that means solar ultraviolet radiation, which is the key harmful element of sunlight that drives this. So we found that. And then of course we went into the prevention trial after the risk factors.

Clare Blake:
It was really interesting the way you measured the photo-ageing.

Prof Adele Green:
Yes, we took dental moulds. We found out, after a little bit of experimentation, that if you put the resinous material that dentists use to take moulds of the teeth, if you lay that quick-drying resin template on the back of the hand, peel it off… In fact, if anyone just looks at the back of their hand, they can immediately get an instant snapshot of how sun damaged and photo-aged they are. And if you’re a little baby, [they have] the best skin of all: The skin of the back of the hand is resilient, that means it bounces back when you push into it; there’s not a crease anywhere. It looks just like a beautiful, flat, homogeneous surface. Then you go to the other age end of the spectrum. And it’s not just age. As I said, if you’re severely photo-damaged, even if you’re young, there is absolutely no bounce back in the skin because the ultraviolet damage destroys the elastic tissue. And that’s why you see that flat, rather featureless skin of older people. Unfortunately, you start getting pigmentation changes and that deep scoring everyone knows. If you see, say, a sun damaged neck, you can see just exactly what I’m talking about. So deep crisscrosses underlie what we see when we look at each other’s faces, and we can see people ageing, most of it is, in fact, due to the sun damage that I’ve just described now, where the elastic tissue is destroyed. You know how if you leave a rubber band out in the sun, anything with elastic in it’ll just perish? Well, I’m afraid that’s exactly what happens to our own skin, and that’s why it gets flat, featureless, and damaged. And that’s the first degree of it. And yes, we can tell that just by looking under the microscope at the imprint from the back of the hand. That’s going to be one of the first signs that you have got sun damage and you’re on the way to possible cancers.

Clare Blake:
Then the exciting bit, Adele. You were the first person to prove that applying sunscreen can prevent melanoma.

Prof Adele Green:
Let us say this: We were the first group here to actually do a human scientific trial, randomised trial – which has the highest level of evidence – Clare. Yes, that’s what we did. Scientists don’t like using the word prove, but our evidence is probably the strongest that we’ll get for the second skin cancer I told you, which was squamous cell carcinoma. We looked at sunscreen in particular. And maybe I could just step aside and say advocating sunscreen as a preventive is only one of many prevention measures that we have at our choice. And I would really want to say to listeners that the main way of preventing sun damage is not using a chemical sunscreen, but first and foremost, for being aware of when sun is at its most intense and most damaging, which depends on the time of the year, the time of the day, cloud cover, how high altitude you are [at], and the surface in which you are – whether you’re surrounded by bright concrete and sand, which are highly reflective and actually almost double your dose of ultraviolet that’s just coming from the sun, or whether you’re in a greensward, or whether you’re in a water situation. All of these things matter. I, as a prevention advocate for skin cancer, would always encourage people to, firstly, use sudden avoidance, secondly, use hats, long sleeves; so much better than wearing a chemical if you can. Deep shade is number three, and then sunscreen comes as the complement to all of that, because of course there are many situations where you can’t wear clothing cover on the beach and in and out of the water.

Clare Blake:
If you’re a nudist.

Prof Adele Green:
And if you’re a nudist, of course. And if that’s how you feel, of course, the first thing you would do, well, you won’t go out in the middle of the day in your nudity, will you? You’ll just keep to before 10:00 and after 2:00 or 3:00. If you’re in a boat fishing, swimming – so then it comes to the sunscreen. And I just really wanted to underscore that, because while it is extremely common and very popular amongst people, it is certainly not the go-to first way we should protect ourselves. It should be looked on as being just one of a whole suite of things that we as Australians and people who are at risk of skin cancer should be doing all the time. Everyone knows that hats prevent skin cancer and long-term damage. Everyone knows about shade. Everyone knows keeping out of the sun, again, is going to be good. No one knew about sunscreen. So what we did was take the best available broad spectrum sunscreen that was available and we randomised it, which means, pretty well, flipping a coin to say each person in the community who agreed to help us would be taking a 50 per cent chance of being randomised to either daily use of the sunscreen that we provided, or they would just keep on using their sunscreen at their normal rate, which usually meant almost a hundred percent of people would not use sunscreen every day. So that was the big difference between our trial. And Clare, no one had ever done that before. And we asked them to do that for five years – to use the sunscreen every day, no matter whether it was rain or shine, to put sunscreen on in the morning. If they went swimming, always reapply it if it was washed off or toweled off. And normally, of course, we would put sunscreen on every two hours anyway. And this is what our people who were helping us in the trial, our participants, did this for five years, almost five years, and then we analysed the data. We found, firstly, the very most common skin cancer, called basal cell carcinoma, or BCC, actually didn’t show any change. But what we did show was that the second most common cancer and the more serious of the two commoner skin cancers, SCC, or squamous cell carcinoma, had a 40 per cent drop in the people who were using sunscreen every day, compared to those who were not randomised to daily [sunscreen] use. We then consolidated that result about eight years later, because you wouldn’t think that – it’s not like switching a light on and switching it off – that suddenly the effect of sunscreen will be immediately evident, and found that that effect had really intensified. So what we are showing is that screening out [ultraviolet radiation] for all those years in those adults – and all those years, it was really only five years and in adults already – that we could have a long-term effect on the skin cancer, because, of course, you’re cooking the skin cancers – to speak like that – by your everyday sun exposure all over that time. So we were blocking out all of that causative sun exposure, and we really saw the full result, and the major result, not ‘til even up to eight years, 10 years later. Those people were benefiting from the five-year intervention. It just shows you how powerful screening out ultraviolet radiation can be, short term, medium term. And of course, if they kept on using it – and a lot of our people did – then they were protected very long term from the skin cancer.

Clare Blake:
The results had a big impact. Do you have a statue in Nambour, Adele?

Prof Adele Green:
No.

Clare Blake:
We’ve heard for such a long time that the damage is done early, but that’s a great case for putting on sunscreen at any age.

Adele Green: 
Oh, that’s a very good point Clare and I’m very pleased you picked that up, because I think that it is one of the major, hopeful points that come out of our research is to show that it is never too late to prevent even those skin cancers developing and being clinically diagnosed by capping it by putting on the sunscreen. Looking at you and I, both with our fair skins, probably assuming that we both had summer holidays when we were young in Australia, I could guarantee now that both of our skins have a lot of mutations and a lot of sun damage. But if we, as adults, can protect our skins now… Skin cancer development is a multi-stage process. And if we can just stop it halfway through that transformation of the benign skin cells – those poor old damaged skin cells that are carrying some mutations… But protecting from further ultraviolet will actually protect from that cancer rolling out to be a fully developed cancer because we are stopping what’s called the promotion of the ultraviolet light. So thank you, and I’ll say again, it is never too late to [start] preventive behavior. It will save your skin from further damage in the long term.

Clare Blake: 
People get caught up in sunscreen. There’s particles, it’s dangerous, prefer the roll-on, and then there’s the spray. I don’t know if you’re happy to weigh in on that debate, Adele?

Prof Adele Green: 
Well firstly, so far, I can say just in very brief summary Clare, there’s been a lot of work done on side effects and harmful effects, but there is no compelling evidence that there is any long-term effects of sunscreen use. I could just go straight back to the Nambour trial, a paper that we just published last year looked at mortality, because some people have even said that the effect of sunscreen shielding out the ultraviolet light actually has other effects on our body’s system – besides preventing skin cancer – that could be injurious. And they’re even saying that this could even affect our mortality rate. After a very long-term follow up, we’ve looked at all of our people in the Nambour study, and there is absolutely zero effect on mortality. Their health was not at all damaged. And so this is a very long-term… 20 years after the [event], we saw no effect at all on hardcore deaths, which is what some people surprisingly have raised. But then stepping back from that, from the things that most people would be worried about or concerned about – dermatitis, does that affect, or allergy? Very rare. And what we found was, when we have 1500 people using sunscreen, yes, probably about three per cent developed what we would call a contact irritant dermatitis. All we had to do then was substitute a different product for the product that was causing them irritation.

Clare Blake: 
That’s just one for baby’s sensitive skin?

Prof Adele Green: 
For example. There’s so many on the market. Of course, if we’re in Australia or New Zealand, the standards here mean that whether you get a very cheap or a very expensive sunscreen, you are covered in exactly the same way. The chemicals in there will vary. In fact, of course, it’s the lotion that’s in – what we call the vehicle that the actual screening products are in – [that’s] probably what is causing the irritant effect. And so you just have to really shop around to find a product that feels good on your skin and is right for your skin. Nanoparticles? Again, that’s the problem with, say, titanium dioxide or zinc – very fine particles. The concern has been that they might penetrate into our upper parts of our skin and get into the bloodstream. But that seems to be unfounded so far and certainly not getting into the kidney or anything like this. So again, there is no evidence to date, over quite a long period of time, that that is a concern. I would counsel people not to use spray-on. You can’t tell how much you’re getting. Of course, it’s a very simple way to try and get sunscreen on very mobile children, who are not willing to sit in a docile fashion and have their sunscreen applied. I’m afraid that spray-on is hit and miss, and it will not give you an even coverage, which is what you need. Roll-ons, again, a little hard to tell just how much you’ve got on. The best way is actually to put it in your hand and to apply it. What I would say is that you make sure that you’re adequately covered. Adequate means you can feel when you’ve put something all over, as much as you can onto your skin. It feels moist. In fact, to reach the amount that the SPF value, the sun protection factor value, has been judged on, it actually feels too much on our skin, too uncomfortable. And that’s why we’re actually criticised, we as humans, when we’re putting sunscreen on, that we don’t put on quite enough. And that’s why we really do need to reapply it, because when you put it on at a thickness of two milligrams per centimetre squared, which is the recommended one, if you and I put that on now, we’d feel we’d have too much excess of fluid on our skin and we’d want to wipe some off. That’s how you know when you’ve got adequate sunscreen on is where you feel almost to the point that you’ve got it dripping off you.

Clare Blake: 
So technically we need to smother.

Prof Adele Green: 
Within reason, because obviously you have to hold things, and you also don’t want the sunscreen running off in your eyes when you’re sweating. So I would say, put it on so that you’re comfortably covered. The key thing is reapplication. We’ve done some very rare work here to show that, actually, if you reapply within a couple of hours, the sunscreen, you can increase, actually, the SPF of the sunscreen coverage that you’ve got. So that’s a very good tip that I think a lot of people think that they put it on once and they’re protected for the day. Not so. And of course, particularly not if you’ve been sweating or bathing or swimming.

Clare Blake:
You need to wear sunscreen for incidental exposure, so basically going from your home to your car in the morning, from your car into your office. Say that you do that, will that still be there in the afternoon, or you need to reapply it again when you go home?

Prof Adele Green:
If you’re outside through the day, you need to reapply it. So yes, that’s exactly what the Nambour study showed. Everyday sun exposure is what accumulates up. And that is what will give us those shocking rates of photo-damage that I told you that we can even see in young people, because people just don’t think to put on their sunscreen if they’re just, say, going to work in the morning and being at the bus stop, or sitting out in the park in the middle of the day. If you are outdoors for longer than one or two hours in the middle of the day, yes, you do need to reapply it. But let’s say you’re an office worker, then putting it on adequately in the morning, just going to the bus stop, going out and coming back in the afternoon, that should keep you adequately covered.

Clare Blake:
There’s a lot of home recipes on the internet for sunscreen, Adele.

Prof Adele Green: 
Oh, I didn’t know about those, and I don’t think I want to know. I think I’m totally…

Clare Blake: 
That answers the question. I think we’ve covered it. There’s one thing I wanted to ask about sunscreen and that is there’s two different types of protection in the way the sunscreen works, isn’t there?

Prof Adele Green: 
Yes, I’ve mentioned before when we were talking about nanoparticles, there’s the physical barrier – titanium dioxide, the zinc oxides – and they are what you can see when you put on your sunscreen. Before we used to have the nanoparticles, you used to see quite glowing and visible application when you put it on, and people didn’t like that. That’s now been more refined by the nanoparticles. And then there’s the chemical barriers, which are the oxybenzones and various other chemicals that are in the sunscreens. The latter are not so visible, [are] easy to put on, and [are] not so opaque and therefore a lot of people tend to prefer those. But of course there has been some aspersions raised by a couple of the chemicals in there. None of those have had evidence against them exactly, except there have been issues raised with the environmental protection that might be needed against some of these chemicals. And we do need to watch that. So I think people are aware of that, and further work is looking at developing safer, shall we say, chemicals for the environment as well as for people.

Clare Blake: 
You’re not going to run out of things to study in the very near future are you Adele?

Prof Adele Green: 
I know. I think this is an ongoing issue. And really, one of the biggest issues that I see for the future is looking at cosmetic tanning and the whole idea in our society that a tan is a cosmetic benefit and is attractive. Of course, that wasn’t always the case. A century ago, it was quite the opposite. People who had any browning of the skin were looked on as artisans or low class and not at all prestigious. Through the early part of the 20th century, this underwent, gradually, a huge change. And now, of course, we’re faced with a society that is seeking to be brown-skinned when they’re white. To me, this is one of the great future aims that I would like to see in my drive for prevention and passion for preventing skin cancer is, how can we switch this cultural norm back to the peaches and cream complexion rather than worshiping the tan? This is still an enormous problem. And it’s been matched with… so-called beautiful people in fashion magazines are highlighted as having browner skin and looking tanned. And there’s other ideas of iconic ANZACs coming back with their tans. So there’s quite a lot of complexity in the psychology of this. And another very interesting aspect of why we think tans might be healthy goes right back to the sanatoria of tuberculosis days, because the people with TB, of course, were put out on verandas. And the ones who came back ‘well and cured’ were the ones with the tan, because they’d been outdoors in this outdoor cure, which was the fashion in the TB sanatoria. And that was probably one of the biggest drivers for skin tanning as being associated with health, going right back to that. So you are so right. We are very complex. But unfortunately, the myths and the traditions that we’ve carried with us are not all leading to our good health.

Clare Blake: 
It’s extraordinary. And I know you just think the best possible treatment for melanoma is not to get one.

Prof Adele Green: 
Of course. Yes, my main mission is to prevent people getting skin cancer, or, well, let’s talk about melanoma. That is by far and away the best way of controlling skin cancer and melanoma is simply not to get it. And that’s what we do by prevention. If we can’t do that, and we’re unlucky enough already to have damage, and we already have our skin cancer developed, or a melanoma developed, then what we need to do is capture it when it’s curable, recognise it early, and to have it excised. If you have a melanoma that is less than one millimetre thick at time of diagnosis and is excised, you have a 96 per cent chance of being alive 20 years later. I mean, that’s as good as being cured. Not true for absolutely everybody, but very high rates of cure. And I’m very pleased to say that, really, around the world – led by Australia, because our problems were so great – but now we can see that the thinner and thinner melanomas have better and better cure rates. And melanoma has now become from a feared and fatal disease to a curable disease because of people’s alertness. I’m making a general statement here, because of course there are a group of people who, even young adults still, [are] being diagnosed with thick melanomas. They unfortunately have a very, very poor survival. Even though we have now wonderful new treatments that have been developed in the last five years, I don’t know that we could still say that we have a cure for those people. And there’s a lot of side effects from those very, very powerful drugs. So that comes back to the point, best of all is prevention, second best of all, get it when it’s early. Know the signs of it – a pigmented lesion that looks like it’s changing, getting darker, growing, newly appeared where it just doesn’t look right, if it looks out of character. You can have a lot of moles. That’s not what we’re talking about. It’s where something new appears and looks to be different to the rest of its surrounding skin, go and see your doctor. And then after that, the more advanced, then you’re in the hand of the oncologists. But there’s hope there, even as I mentioned, because we’ve got very, very powerful new therapies now for advanced melanoma, as well, with high survival rates.

Clare Blake: 
What’s the current focus with your group right now, Adele?

Prof Adele Green: 
I’m very interested in nutrition as a supplement. And so we’re looking at nutrition, both in high risk people for melanoma, but also we’re looking at people who have organs transplanted. Those people are at one of the highest risks in our whole community for skin cancer. And a lot of people don’t realise that to stop having their transplanted organ rejected, they must be on very high doses of immunosuppressant drugs. And unfortunately that means that they can’t reject their skin cancers either. Heart transplant and lung transplant patients are particularly at risk of this because those organs need very, very high immunosuppression to keep the donor organ. Those patients are really very smitten with skin cancer. So we’ve tried fish oil trials and had very promising effects out of that. And now we’re currently looking at other aspects of omega-3. But also we’re looking at antioxidants in the diet, which come from fresh fruit and vegetables. So that’s one big aspect of our work. On a totally different aspect of our studies, people who are diagnosed with localised melanoma and what makes that melanoma come back in the future. So that’s another big aspect of our work.

Clare Blake: 
Thank you so much. It’s been fascinating. Thank you to you and all the people of Nambour, because it’s getting harder and harder to find people to volunteer for studies.

Prof Adele Green: 
Yes, we were very blessed with the rapport that we developed with that community. I’ll be eternally grateful to them and to the support groups that we had from that community. I think Nambour’s gone down into the skin cancer history for research, and they know our gratitude.

Clare Blake: 
To recap, or to find out more about Professor Adele Green’s incredible body of work and her current focuses, go to qimrberghofer.edu.au. Thanks so much, Adele.

Prof Adele Green: 
It’s a great pleasure, Clare. Thank you.