Skin in the Sun
The first thing that sunlight hits when it meets us is mainly our skin, and Adam Murphy’s been finding out about some of the positive and negative consequences when that happens from …
Adam - It is nice to get out in the sun, especially if you've been cooped up during lockdown or during winter. The light is nice, the warmth is great, and getting some sun on your skin has some real benefits.
Sarah - There's two effects that exposure to ultraviolet radiation from the sun can have on our skin. The first of these is that it can produce Vitamin D. Like other vertebrates we are able to synthesise Vitamin D; the ultraviolet radiation in the sun is responsible for that synthesis. So that's sort of the healthy bit of sun exposure, if you like. And it doesn't take very much sunlight to be able to do that. But here in the UK, that only really works for about six months of the year. So basically from October through to the end of March, there's not enough ultraviolet radiation hitting the UK for us to be able to produce that Vitamin D.
Adam - That is Sarah Allinson from Lancaster University about the importance of Vitamin D. If you don't get enough sunshine it can cause problems like rickets. But as she said, you don't need a lot of sunshine to feel the benefits, and you can definitely get too much - when the ultraviolet rays of light from the sun damage your skin and cause a nasty burn. Now usually the buddy is pretty good at repairing itself, but...
Sarah - ...but if that doesn't get repaired, or the skin cell doesn't die, then what can happen is you have mutations in genes that control the processes which determine whether a skin cell is able to grow or not. So in the body, the growth of cells is very, very tightly regulated. And cancer is what you get when that process of regulation of cell growth is disrupted. And so you go from the DNA damage, to mutations in the genes that control that process of cell division, and then that can lead to cancer. And that gap between the exposure to the ultraviolet radiation and the cancer can be quite significant. It can be decades in some cases.
Adam - Cancer is a myriad of different problems, though, and there's not even just one kind of skin cancer.
Sarah - There are two main types of skin cells that we need to think about when we're thinking about skin cancer. The majority of skin cancer cases arise in a type of cell called a keratinocyte, and that's what makes it most of your epidermis, the skin. And those skin cells have been continually renewed, have been continually sloughed off. When those become cancerous, they produce this non-melanoma skin cancer, the main types being basal cell carcinoma and squamous cell carcinoma. In general, those types of skin cancer are less fatal than the other type, but they do comprise the vast majority of skin cancer cases that are diagnosed every year - about 150,000 new cases of non-melanoma skin cancer diagnosed just in the UK every year. Those, as I say, tend to be less harmful, because they are less likely to spread around the body. The more harmful type of skin cancer is cutaneous malignant melanoma. And that's the type of cancer that arises in specialist cells that are found within our skin that are responsible for choosing pigments. So basically they're the cells that enable us to be able to tan when we're exposed to the sun. And those types of cells are often able to spread. And for that reason, they tend to produce cancer that can be more dangerous. And so although there are only 16,000 cases of malignant melanoma diagnosed in the UK every year, it's responsible for almost two and a half thousand deaths. So it is much more dangerous than the other type of skin cancer.
Adam - The easiest way to protect yourself is to avoid the sun and to wear sunscreen. The problem is that most people don't use nearly enough. You need a thick layer to get anywhere close to what's written on the bottle. And even then you need to keep reapplying because it can rub off, wash off, or even degrade under sunlight. But let's say you're doing your best - and you're still nervous. What should you look out for?
Sarah - The most important thing that people can do is to be aware of their own risks. So people who are more at risk of UV damage are people who have very pale skin, a tendency to freckle; if you tend to burn in the sun, then you're going to need more sun protection than somebody who has darker skin. So that's one thing to be aware of. The other thing is to be aware of your skin and to look out for any changes. One of the things that's come up during the pandemic is a lot fewer people have been going to their doctors with suspicious moles. And so the number of skin cancer cases that have been diagnosed in the past year has decreased. And I don't think that's because there's fewer cases; it's just they're not being picked up. And what we know about skin cancer, as with any cancer, is the sooner you are able to diagnose it the better. So if there's anything that you see that just appears a little bit unusual, then it's a good idea to make an appointment with a doctor and get them to check it out.