Sunscreen Tips

M. D. Anderson Cancer Center
Date: May 2008

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Dr. Susan Chon, assistant professor of dermatology at M. D. Anderson Cancer Center, speaks about sunscreen during a lecture on skin cancer prevention.

Photoprotection. This is what we generally tell patients and this is something you can apply to your own lives, avoiding the sun. That's the first line of protection, not sunscreen. Sunscreen is the last line in my book, but everyone thinks that's the first thing. The first thing is avoid the sun. If the sun doesn't hit your skin, you're not gonna get sun damage.

So number one is don't go out between 10 to 4. Everyone's like, that's a long time. Well, it is especially in the summer months, when you see how high the sun is still at 4 o'clock. It's very intense. So try to do your activities earlier or do it later. And somebody'll say, well I don't have time, I have to do it at noon, that's okay, you have to live your life, but be sensible and use some protection during that time too.

Wear tightly woven clothing. There's a lot of sun-protective clothing and we'll talk about that a little bit later. I'll show you some examples. And then wear a wide-brimmed hat that provides shade for your face. Again, that prevents the sun from touching your face. So these are all things that are gonna block the sun from actually hitting your skin. And then protective sunglasses are really important. People squint a lot and that's how they develop the crow's feet around their eyes with a lot of squinting. But also you develop a lot of cataracts. So wear sunglasses when you're outdoors as well.

And the next line, which I think is the third line of protection, is actually wearing sunscreen. And there's some very good sunscreens especially nowadays. And they should be at least an SPF 30 and why do people say I have to apply it 30 minutes before I go out. Well, if you apply it right before you go out and start sweating. That liquid that you just applied on your skin, it's still liquid and it's gonna just run right off with your sweat, but if you let it set and dry a lot of these are more powder, they kind of attach better to your skin and so they're more water resistant. So apply it sometime before you actually go out and do anything.

The last thing is do I need to reapply? Yeah, you need to reapply if you're swimming because that basically no matter what kind of swimming you're doing, it's coming off in that water and also if you're sweating a lot. If you're out there playing golf or tennis or gardening, and you're doing it for extended hours, you need to reapply.

As I mentioned the sun-protective clothing, sunprecautions.com has a clothing line called Solumbra and that's actually a medical device that's approved by the FDA. So it's not some fly-by-the-night company. This is a medical device that's been tested. It does what it says it's gonna do and it blocks 97 to 99% of the UV rays. And it's not a chemical. It's actually the weave of the fabric and the type of the fabric.

Coolibar.com is another very reputable company and they both have as I mentioned the pants, shirts. They have sun-protective gloves for driving, they have sleeves for driving. I have some truck drivers and their left arm and the right arm are like two different people. So they wear a sleeve on their left arm, they have great sunglasses, sunscreens, wide-brimmed hats, pretty much anything you can think of, they've made it. And they made a lot of swimming clothes and basically protective clothes for children as well. Now, that can get pricey because some of these are expensive.

So the other thing that you can do is to treat your clothing and this is with a product called SunGuard. There's a chemical that's called Tinosorb and you wash your cloths in the actual chemical and then it lasts for about 20 washes depending on how you wash your clothes, but then they can be reapplied again. Just make sure, you know you're not allergic to it, you might test a couple of clothes, shirts, out first, but it also works really well for children because they change clothes so frequently. It's just to protect their clothes that they wear to school everyday.

And sunscreens, do they work? Yes they work if you use them and use them right. So they protect you from sunburns, but they also protect you from photoaging and people don't really care about that when they're young, but then as they get older they say, well I didn't know. And that's why we're telling you early, do it now. It doesn't show up right away. It shows up later.

And also people have some things called photoallergic reactions. Certain medications, certain diuretics, or like water pills, blood pressure medications, they can actually cause you to have an allergic reaction when it's combined with sun exposure. So there's certain medications that patients need to be aware of and often times their doctors and their pharmacists will let them know, but if they have a photoallergic reaction, they still need to take their medications and they definitely need to use all the sun-protective measures we talked about.

Photosensitive skin conditions that certain people have, actually conditions where they're kind of allergic to the sun and those patients again when we get them to use their sunscreens pretty much helps them to be able to go outdoors and do their regular activities. And then of course the final and one we stress the most is induction of skin cancer.

There are two main types of sunscreen. It's very confusing because nowadays, there are -- especially when it comes spring, there are huge displays, with like a gazillion sunscreens. So the main thing is to look at the active ingredient.

Physical sunscreens are actually made of zinc oxide or titanium dioxide. That's a mineral particle, and now they're so finely micronized. It's not that big, thick white paste people used to use in the 70's. I mean, I have it on, you can't see it, it's actually very well made now. And they're really good because they kind of reflect and scatter the light.

The second main type is chemical and these are all the ones with really long strange names. And these are actually ones that absorb and remit the light, and these sometimes can cause more sensitivity because these are actually chemicals. And here are just some real common ones. So I mentioned the UVA and UVB chemical sunscreens. These are like salicylates, methoxycinnamates, avo-benzones. There's lots of these different long names.

And one of them actually is kind of new, at least new to the United States and it's called mexoryl. It's this one right here and it's been around in Europe and Japan for about 15 to 20 years. It has a very good spectrum of coverage for the UVA rays. And right now, it's still available in Canada and we've only approved the SPF 15 version of this, but right now the only two places that carry it are Lancome. It's called Lancome UV Expert and the other one is the Anthelios and they have an SPF 15 and they're both made by L'Oreal, La Roche Posay.

The UVA, UVB absorbs I mentioned the zinc oxide and the titanium dioxide, those are physical sun blocks and these are not chemical. These are actually physical particles. Another good one though is benzophenone and it blocks both the UVA and the UVB. So, when you're looking for a sunscreen, you kind of want something, you know one of these ingredients hopefully. And if not, you want a combination of this and one of these. Because you wanna make sure you cover both parts of the UV spectrum.

SPF, you know what SPF measures? It only measures UVB. So, that's why, it's a little faulty because, back then they only thought UVB was important. So yes, when they tested each of the chemicals, they cover a little UVA. So, they kind of a yeah, it's UVA/UVB protective because it did, it wasn't a lie. It's just that the way they measured it, they really only measuring the UVB protection and the UVB protection was measured in SPF and SPF is just a ratio. And as this shows you is the a mount of UV exposure with the sunscreen that causes redness versus the amount of UV light, you had to get before, you know without sunscreen that would cause redness. And let me show you the example. A person can spend a hundred minutes in the sun with the sunscreen before he turns red versus ten minutes in the sun without a sunscreen before turning red. Therefore, what is the factor? It's a factor of ten, so the SPF was 10.

This is a very, very, kind of vague system. And so the American Academy of Dermatology, the American Cancer Society has been pushing for changes in the SPF ratings and they're moving to, and they've been saying that for a couple of years, of low and high and I'm not sure when that's gonna get rolled out, but it's actually going to be low and high and something that covers both UVA and UVB. So this is an old system and this system that's really isn't kind of up-to-date with what we know about sun damage and skin cancer formation.

So, what are some adverse effects because there's adverse effects to everything and one of the common things is that I have patients who come in. I had someone yesterday who was allergic to a sunscreen. So, when someone's allergic to sunscreen, you first try to tell them that this happens, let's look at what sunscreen you tried because sometimes, you're just allergic to that one active ingredient. And then you just switch to a different one that doesn't carry that active ingredient.

If they are overall just very sensitive, I just go and get them straight to the physical sunblocks. And most of those are labeled sensitive skin or baby. When you look at those labels, they're usually have at least partial physical blockers, like the zinc and titanium, with a little bit of the chemical, but if you're really interested in some of these purely physical blockers, I can give you some names of those as well. And those are the ones that only contain physical sunscreens. There's always another risk of course that's not the active sunscreen, sometimes it's actually the vehicle that means it's the lotion, that it's in, it's the perfume that's in there, it's the actual anti-bacterial they've added to that liquid, but a lot of times, it is the active sunscreens so try a different one. Don't give up.

And again, I mentioned the zinc and titanium, it's great. I especially recommend that to patients at the cancer center because they are already extremely photosensitive from their other treatments, from their radiations, from -- lots of other meds they're on. And so the physical sunscreens is where I go to first. I don't go to the chemical sunscreens at all actually.

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