Wear your sunscreen. It’s an age-old rule that you’ve likely been told since you were young. You may have even learned this rule the hard way – especially if you live with vitiligo. But have you ever wondered why your dermatologist – or perhaps your mother – stresses the daily use of sunscreen?
Today we’re going to break down the science behind why sunscreen is so critical – and what it means for you if you live with vitiligo.
Why the sun can be harmful to your skin
Why is the sun harmful to your skin in the first place? You might already know that the sun’s rays can, at times, leave you with painful burns that last days. This is because melanin, your body’s natural protection against the sun, can get overwhelmed. When this happens, we get a toxic reaction called a sunburn. When it is severe enough, we can even get painful blisters (ouch). But did you know that those same rays of light can cause cancer? In fact, even a single sunburn increases your risk of skin cancer.
How does the sun cause skin cancer? Here’s a quick science lesson. The sun emits a combination of powerful light rays that we can differentiate by their wavelengths. The most dangerous of these light rays is called “Ultraviolet B” or UVB for short. UVB’s specific wavelength gives this type of light ray extremely high energy. In fact, its energy is so powerful that when it hits our skin cells, it can change the structure of the DNA in those cells. Fortunately, we have mechanisms that can repair the damage, but it is not perfect and sometimes our cells can miss errors in our DNA during repair. When that happens, cancer can form.
How your skin protects you from the sun
You might be wondering: If UVB is so damaging, then why doesn’t everyone who goes out in the sun have skin cancer? We have the largest organ in our body to thank for this.
Our skin is an important barrier that protects us from the damaging effects of UVB. In particular, there are two main cell types that contribute to this barrier. Keratinocytes are what we can refer to as “skin cells” and are the main cell type that covers the entire surface of our body. When keratinocytes sense UVB rays hitting our skin, they signal to a neighbouring cell called the melanocyte. Once the melanocyte receives the signal from the keratinocyte, it makes proteins called melanin – the hero of this story – which act like a shield to block UVB rays from damaging DNA.
So what does this mean for vitiligo?
What experts say about the sun and vitiligo
As the astute student you are, you might then ask: If individuals with vitiligo lack melanocytes, wouldn’t they be at an increased risk for sunburns and skin cancer? The answer might surprise you.
Those living with vitiligo – and therefore lacking melanocytes as a result of vitiligo – are more likely to experience sunburn as a result of sun exposure. However, the same isn’t true for skin cancer, contrary to popular belief (and possibly common sense).
A 2018 study and report on existing research shows that there is actually less incidence of skin cancer in people with vitiligo when compared to the general public. Scientists have come up with possible theories as to why vitiligo might be protective against skin cancer but the reason is still largely unknown.
“It is completely understandable that dermatologists assume that the risk of skin cancer is high in patients with vitiligo,” said Dr. John Harris, a dermatologist and physician-scientist who is also the director of the University of Massachusetts Vitiligo Clinic and Research Center. “But the available evidence does not support this.”
Dr. Harris also reinforces that it is still possible to get skin cancer if you live with vitiligo – there just isn’t an increased risk. And this is why sunscreen matters.
How sunscreen and sunblock protect your skin
Despite all of the complicated science behind sunburns and skin cancer, the solution is quite simple: sunscreen and sunblock. And yes, there is a difference between the two.
Sunscreens use a chemical reaction to fend off UV light and are also conveniently named “chemical blockers.” When sunscreen is applied to the top layer of the skin, the active ingredient absorbs harmful UV rays and converts them into small amounts of heat that easily and safely dissipates from the body. Sunblocks, on the other hand, are termed “physical blockers” because they form a physical barrier that prevents UV rays from reaching DNA.
Both sunscreens and sunblocks provide SPF protection. SPF stands for sunburn protection factor and refers to the degree of protection a certain substance offers against the sun. As a reminder, your melanin offers natural protection. However, this protection is assumed to only have an SPF of 1.5-2.0 – this is true for all skin tones and is not enough to keep you safe from sunburns and skin cancer.
Dermatologists recommend using a daily sunscreen or sunblock with an SPF of at least 30. This means that even when our body cannot make melanin as fast as we need it, we can rely on chemical and physical blockers to protect us from both sunburns and skin cancer.
The bottom line – wear your sunscreen
If you are thinking of planning a sunny trip to the beach or the park, don’t let having vitiligo get in the way. Experts say that there is no need to avoid outdoor activities you love as long as you remember to wear your sunscreen. You can go in the sun if you have vitiligo – you just need to be safe.
Brenner, M., & Hearing, V. J. (2008). The protective role of melanin against UV damage in human skin. Photochemistry and photobiology, 84(3), 539-549.
Ban, L., Labbouz, S., Grindlay, D. J., Batchelor, J. M., & Ratib, S. (2018). Risk of skin cancer in people with vitiligo: a systematic review and meta-analysis. British Journal of Dermatology, 179(4).
Erika Malana is a medical student from Toronto, Canada. She is interested in how everyday agents and stressors, such as pollution and UV light, can contribute to skin cancer and hopes to empower future patients through education on preventative health habits. In her spare time she enjoys spending time with friends and family and binging TV shows.