Cheryl Martin (Host): How important is it to use sunscreen, especially during the summer months, to reduce the risk of skin cancer? Here to answer that question and educate us on melanoma and the power of sunscreen is Dr. Justin McLawhorn, a dermatologic oncologist at UAMS.

This is UAMS Health Talk, a podcast from the University of Arkansas for Medical Sciences. I'm Cheryl Martin, Dr. Mc Lawhorn. Glad to have you on.

Justin McLawhorn, MD: Thank you so much for having me. It's always a pleasure.

Host: So, let's discuss sunscreens first. What is the difference between chemical sunscreens (organic) and mineral (inorganic) sunscreens?

Justin McLawhorn, MD: So, chemical sunscreens contain oftentimes a component of a manmade ingredient and a naturally occurring ingredient that absorb the sun's ultraviolet radiation. It absorbs the radiation so that it does not reach your skin. Now, the inorganic or the titanium and zinc-based sunscreens, these are sunscreens that contain wholly natural ingredients that physically reflect the sun's ultraviolet and visible light. So, there's two different types of sunscreens, and this is the organic and inorganic or the chemical and physical blockers, and this is the main way that they function.

Host: So, is it better then to use organic?

Justin McLawhorn, MD: So, that's a difficult question to answer. Oftentimes, people will find themselves preferring the physical or the titanium or zinc-based blockers over the chemical blockers, but many times people will prefer the chemical-based sunscreens just due to the ease of application. Many people don't understand or don't rather know the difference between the chemical and the physical blocker just by looking at the label. And it's important to try to understand that.

The chemical blockers, those are oftentimes the sunscreens that are a spray or they come out as a lotion or a gel. These are the ones that you'll need to reapply frequently, every hour to two hours. And these are the ones that as well have gotten into the news recently as being a component of a concern regarding coral bleaching, whereas the titanium-based or inorganic, the physical blockers, these all come as a cream or a lotion. These have a inherent UVA and UVB blocking ability. These, however, are a little bit harder to apply or maybe a little less cosmetically sensitive than the chemical blockers because they oftentimes will come out as a white paste. Now, some more expensive ones have been formulated to where they're nearly transparent, and others have been formulated to where they contain a little bit of a bronze or a brown color, which many people can appreciate. Nonetheless, the chemical blockers tend to go on very clear, and the titanium or zinc-based, the physical blockers tend to go on as more of a creamy paste.

Host: So, we hear a lot about SPF. What does that mean and what is the minimum recommended SPF?

Justin McLawhorn, MD: SPF is a sun protection factor. It's actually a ratio. It's derived from the amount of time that you can spend in the sunlight to get burned over the amount of time that you would spend in the sunlight having used that sunscreen and how long it would take you to get burned using the sunscreen. So, it's essentially a ratio of how much longer you can stay in the sun without getting burned, and that's dependent upon the ultraviolet radiation type B or UVB. So, the American Academy of Dermatology recommends a minimum of SPF of 30. However, many manufacturers make SPF of much higher.

Host: And so, of course, that means the higher the better?

Justin McLawhorn, MD: So, that's not exactly true. The higher the number doesn't necessarily mean the better. The higher the number may afford you a minimally better protection in the short term. A higher number doesn't necessarily mean that you're getting essentially more protection. What it really tends to mean is that it's blocking out a little bit more of the ultraviolet B radiation, and it may give you a longer amount of time between your reapplication doses. For instance, if you were to compare SPF 50 to SPF 100, you would think that the SPF 100 is nearly twice as protective as the s pf 50. Well, that's not exactly true. That's actually just a couple of percentage points difference in between how much ultraviolet radiation B you were being protected from.

But what may actually be of some benefit between SPF 50 and SPF 100 is, again, the length of time that you can spend in the sun without being burned. That may be something that may be worth spending the more money on to get a higher SPF. Nonetheless, what's more important than choosing a higher SPF is to choose a minimal SPF of at least 30 reapply every two hours, more frequent if you're sweating or involved in more water sports activities, because this is where the sunscreen tends to rub off or wash off. And so, making sure that you have a sunscreen that you like that is at least SPF 30 and reapplying frequently. That's the best recipe for making sure that you protect your skin from the sun.

Host: Great. Now, what does UPF mean?

Justin McLawhorn, MD: UPF or ultraviolet protection factor is a name which is given to clothing's ability to protect you from the ultraviolet radiation from the sun. It's similar to the SPF, which is rated from sunscreens. UPF is a designation which is used to describe, however, clothing. These clothing that are rated as UPF have to undergo extensive testing in order to achieve a UPF rating.

Oftentimes, the clothing material that is UPF, that is synthetic or manmade. It's nylon, polyester, rayon, spandex, not much cotton. Cotton inherently does not have a high UPF, so that's why it's important even if patients wear long-sleeved shirts and long pants, that they choose the right clothes to protect themselves. Oftentimes these manmade materials that are specifically designed tightly woven and rated with a UPF factor in order to protect yourself fully from the damaging effects of the sun.

Host: And so, on the tag, it would say UPF?

Justin McLawhorn, MD: Oftentimes, the manufacturer would put the UPF directly on the tag. It is something that can and has been marketed. Oftentimes, they'll even put it on the front or near the back of the sticker, it'll say UPF. In addition, it'll give a number very similar to the number that's given on an SPF sunscreen. Look for the shirts and clothes that have a UPF of 30 or more.

Host: Okay. So, you've told us the sunscreen you would recommend. What does broad spectrum mean?

Justin McLawhorn, MD: Sunscreens now have to be labeled with the ingredients that they contain and also the type of spectrum that they protect against. Broad spectrum refers to blocking or protecting against UVA and UVB. I think it's important to pause and also discuss then what is the ultraviolet radiation. The sun puts out three different types of ultraviolet radiation, including UVA, UVB, and UVC. UVC is effectively filtered out by the earth's ozone layer, so it really doesn't reach the surface of the earth. However, UVA and UVB do. So, it's important to be able to block both of those because they both can damage our skin, but in slightly different ways.

UVA is the type of ultraviolet radiation that causes age spots, freckles, fine lines, wrinkles, and it causes the darkening of our skin. Ultraviolet radiation B, UVB, I think of it being as UVB bad because this is the type of radiation which oftentimes is linked to the development of skin cancers, including basal cell carcinoma, squamous cell carcinoma, and melanoma. So, a sunscreen that blocks both UVA and UVB is therefore regarded as being broad spectrum, and this has to be shown on the front, on the label of the sunscreen.

Host: That's important to know. So when we are buying sunscreen, look for information, UVA, UVB, and the SPF number.

Justin McLawhorn, MD: That is exactly correct. And I think that an important point to make is that the physical blockers-- those are the titanium and zinc-- are inherently broad spectrum because their mechanism of action is a reflection of that ultraviolet light. It's the chemical sunscreens that we have to ensure are protective against UVA and UVB. Nonetheless, many manufacturers will still show on the label as if their product being broad spectrum, and it's important that it does say broad spectrum.

Host: You mentioned problems with the skin. So, what is melanoma and how is it diagnosed?

Justin McLawhorn, MD: Melanoma is a cancer that originates from the pigment-producing cells of the skin. There are several different types of melanoma, and melanoma is staged according to how extensive it is. Melanoma is diagnosed based upon a skin biopsy. So, pathology is the only way to give a diagnosis of melanoma.

As a dermatologist, we can have very high suspicions of a melanoma or a melanoma-like lesion, but it is only with a biopsy in which a piece of skin is obtained, sent to a pathologist and then inspected under a microscope that we can then render a diagnosis of melanoma.

Host: What are the ABCDEs of melanoma?

Justin McLawhorn, MD: The ABCDEs of melanoma, and this is a very helpful memory aid in thinking about how lesions look on your skin. This is important to go over.

So, A is for asymmetry. If you were to take the lesion itself-- the lesion of interest that is-- divide it in half, and if it doesn't look the same on both sides, we would call that asymmetrical. That's what the A stands for. B stands for the border, and in particular, border irregularity. The way I describe it to my patients is if you can't see a clean line between the boundary of the spot and the normal-appearing skin behind it, then that's irregular border. If you can't take a pin or a pencil and physically draw it out like you're connecting the lines, that's an irregular border because sometimes when those borders are blurred, that may be an abnormal finding.

C is for color. Color, not only in the type of color of these, of the lesion itself, but also color changes, which we'll get to in here in just a moment. But in general, we like to think of melanoma as having multiple different colors or a particularly rich and vibrant black color. Sometimes melanomas don't have to have any color and can just look like normal-appearing skin. That may be just a little bit red. These are another special subtype of melanoma, but C nonetheless, corresponds to color.

D is diameter. Diameter greater than six millimeters. In general, we don't like to have moles greater than six millimeters, but this doesn't go for every mole. The size of six millimeters just so happens to correspond to the size of a pencil eraser. So if you hold a pencil eraser to the spot that you're concerned about and it seems to come go outside that or be bigger, that might be something worthwhile to discuss with your dermatologist on your next skin check. And so, that's D for diameter. E is evolution or change with time, and that's what I was hearkening to a little bit earlier in terms of the color. Because melanomas cannot just change in size, shape, they can change in color, they can even change in contour. They can also even become raised. These are changes that are important to mention and to discuss with your dermatologist when you do get your skin checked.

Now, not all of these taken by themselves means that any particular lesion is particularly concerning or worrisome, but however taken together, taken as a whole, sometimes these can be used to help one recognize what spots on their body need to be more closely monitored and brought to the attention by a dermatologist. So yet again, another useful tool to help us identify more concerning spots.

Host: So, does using sunscreen indeed decrease the risk of melanoma?

Justin McLawhorn, MD: It does. Studies have shown that with increased rates of using sunscreens, decreased rates of melanomas. We know this from population-based studies. We also know that using regular use of sunscreens can also decrease the rates of new skin cancers other than melanoma, including basal cell and indeed squamous cell carcinoma.

I think that the evidence supports more the use of sunscreen to prevent basal cell and squamous cell. But nonetheless, we do know that seeking shade, keeping out of the sunlight, prevention of burns from the sunlight sunburns, and wearing sunscreen routinely in order to help to prevent sunburns can decrease the rate of getting melanoma, particularly in people who are genetically susceptible.

Host: Can people with darker skin types get melanoma?

Justin McLawhorn, MD: Absolutely. People with darker skin types can get melanoma. However, the rates of melanoma are decreased, again, because we believe that the majority of melanomas are driven by mutations that are conferred from the ultraviolet radiation in the sunlight. Having extra pigment in the skin can be protective.

There's one in particular subtype of melanoma that comes to mind in patients with skin of color, and that is melanoma of the hands, melanoma of the feet and melanoma of the nail units. These tend to be overrepresented in patients with skin of color or darker skin types. But yes, people with darker skin types and people with skin of color can still get melanoma. And that's why it's also important to see a dermatologist in order to have routine skin checks. And unfortunately, it's these patients who have the darker skin types that tend to think of themselves as being more protected, that tend to not see a dermatologist and then have a cancer diagnosed at a higher stage. So, it is still very important. Regardless of what your skin color is, regardless of what your nationality and background may be, it is still very, very important to have at least an annual skin check with a dermatologist in order to ensure that all of your spots and all of your skin checks out.

Host: What are the current treatments for melanoma, Doctor?

Justin McLawhorn, MD: The current treatments for melanoma is based upon the individual stage of the melanoma. So, melanoma is staged according to how extensive it is. So for melanoma that starts in the uppermost part of the skin and does not invade into the deeper parts of skin. We can use topical chemotherapy to completely obliterate it, make it go away without any surgery. Or we can also use surgery to make sure that our margins as we remove the cancer are completely free of the cancer. Meaning that everything that we remove is contained in that piece that's taken out.

For melanoma that begins to invade a little bit deeper, but not too deep, surgery is still the first line treatment option in order to remove it with clean margins, meaning that all the cancer gets out. When melanoma begins to get a little bit deeper, oftentimes in order to stage or to determine how extensive the melanoma may be, additional investigations should be done. That may be a sentinel lymph node biopsy, and occasionally some images such as a CT scan may be done. And in these cases, oftentimes surgery in conjunction with chemotherapy, or more commonly immunotherapy, may be done in order to help either cure or send the cancer into remission.

Host: So, I just want to clarify, so the only way a person can know if they have melanoma or any other skin cancer is by coming in and getting a biopsy because you don't experience pain. Is that correct? Or are there symptoms?

Justin McLawhorn, MD: There may be symptoms. So, on the patients that I've seen that have had melanomas, many of them don't complain of any symptoms. They didn't even know that it was there. And I find it on a routine skin check. So many, many cases, and I would argue that most of the cases that I see it from my patients and from others alike who sent to me for treatment, they're asymptomatic. But there can be some symptoms. Some of my other patients recently have complained of burning, itch. More commonly for more advanced stages, it may be bleeding or raising up and forming a little growth above the skin. We never want to see that happen. We always want to catch it earlier than that, but that's why coming to a dermatologist who then makes a judgment call or a decision about which lesions should and should not be biopsied, is very, very important.

Host: You have talked about how to protect yourself against melanoma. Any other recommendations there?

Justin McLawhorn, MD: Absolutely. So, not only is sunscreen paramount in protecting your skin from the sun. Other things that you can do is obviously avoiding the sun altogether, but that may not be realistic for people, particularly for people who work outdoors. Wearing wide-brimmed hats can oftentimes protect your head and neck and your nose and your ears in particular. I like to recommend a hat that even has a built-in curtain on it or a neck guard. That way, essentially everything is nearly protected. Long-sleeved shirts, pants as well that have a UPF factor on them. This is a good way to protect yourself, particularly if you find that you're sweating outdoors. It's hard to make the clothing wash off, but the sunscreen can definitely do that. So, the clothing with UPF is definitely a really good idea in these cases.

If at all possible, you can avoid the sunlight between the hours of 10:00 to 4:00. This is when the sun tends to be at its most intense, or more specifically the ultraviolet radiation B, is at its most intense. If you can see the sun and the sun's ray, even if it's on the horizon, then ultraviolet A is out. If the sun's out, UVA is out. But as the sun progresses through midday, that's when UVB is at its highest, and that's when it's time to seek shade. It's oftentimes told that when your shadow is shorter than you are, seek shade, because that's when the sun is at its most intense.

Host: Dr. Justin McLawhorn, you have done an absolutely great job educating us on melanoma and the power of sunscreen. So informative. Thank you so much.

Justin McLawhorn, MD: I'm happy to do it.

Host: To schedule an appointment at the UAMS Oncology Clinic, call 501-686-8000. If you found this podcast helpful, please tell others about it and share it on your social media. You may find other topics of interest to you when you check out our entire podcast library. This is UAMS Health Talk, a podcast from the University of Arkansas for Medical Sciences. Thanks for listening.