Ask the Expert
Staying Safe in the Sun
Skin cancer is the number-one cancer diagnosis in the United States — it’s more common than breast, prostate, and lung cancers combined.
By Susan Godstone
Skin cancers can be divided into two types — non-melanoma (basal and squamous cell carcinomas) and melanoma, with melanoma being the least common but most life-threatening. Each year, some 90,000 people are diagnosed with melanoma. Sarah Arron, MD, PhD, a resident alumna and director of the High Risk Skin Cancer Program at UCSF, shares her thoughts on skin cancer prevention and helps separate the facts from the hype.
What SPF should I choose?
I recommend SPF 30 or higher. SPF stands for sun protection factor, and the SPF number indicates the time it will take for UVB rays to redden your skin when you’re using the sunscreen. An SPF of 15 means you block 93 percent of the sun’s UVB rays; SPF 30 protects against 97 percent; and SPF 50, 98 percent. Most people do not apply sunscreen as directed, so I always steer my patients toward the higher SPF numbers.
What does “broad-spectrum” mean?
It means the sunscreen provides protection from both types of damaging ultraviolet (UV) radiation — UVA and UVB. Both contribute to skin aging and skin cancers. UVB is the dominant sunburn and suntanning ray, whether the ultraviolet rays come from the sun or a tanning salon, while UVA penetrates deeper into the skin, causing premature aging and wrinkling. The SPF number measures only UVB protection, so you need to make sure your sunscreen specifies UVA protection as well.
How much sunscreen should I use?
The recommended amount is a tablespoon for your face and a shot glass (2 ounces) to cover your body. Sunscreen should be reapplied every two hours if you’re out in the sun. And always reapply after swimming; even waterproof sunscreen isn’t resistant to towel drying.
What are the benefits of sunscreens that include moisturizers?
These are a great idea, and you can now buy them with up to SPF 50. If you use one of these, remember to cover your ears and the back of your neck and next to your hairline — places you might not always put a moisturizing cream.
Should I use sun protection on my lips and eyelids?
Lips can be sensitive to UV radiation, but sunscreen is not going to stay on or taste good on your lips. You should wear lip balm with SPF 15. Eyelids are challenging because sunscreen irritates the eyes. Many sunglasses, however, have UV blockers in the lenses, and I recommend wearing those.
Should I choose a chemical or a mineral sunscreen?
Each has its pros and cons. Mineral sunscreens contain titanium and zinc oxide. People with sensitive skin may have less reaction to a mineral sunscreen. Some of my patients prefer minerals due to concern about chemical safety and a preference for a natural approach. The downside is that these may feel thicker and heavier and can leave a ghost-like sheen on the face. Chemical sunscreens include avobenzone and oxybenzone in their ingredients and are usually formulated to feel lighter and appear more elegant. Neither one is more protective. The most important thing I tell people is that you like wearing the sunscreen enough to make it a part of your daily routine.
Are there any ingredients in sunscreens that I should avoid?
Unfortunately, there is no black-and-white answer to this question. As a dermatologist, I am very confident in the data showing that UV light causes premature aging and skin cancer. On the other hand, it’s difficult to prove that any specific ingredient in sunscreen causes harm. That said, I have patients who prefer to avoid sunscreens with parabens (sometimes because of an allergic reaction) or sunscreens with fragrances. It goes back to choosing one that makes sense to you and that you will wear every day.
If being in the sun makes me happy, why should I protect myself from it?
Sun exposure can boost mood, and that makes sunshine addictive for some people. We like to rationalize that addiction by saying it must be healthy if it makes us feel or look good. But it’s not. There is no such thing as a healthy tan, even though the tanning bed industry promotes its products that way. Until we dismiss the idea of a “healthy” tan, we’ll continue to see an epidemic of skin cancer in this country.
If I wear sunscreen every day will it affect my vitamin D levels?
It’s true that one of the ways our skin makes vitamin D is through UV radiation. But there are many other ways to get vitamin D, such as leafy greens, fortified milk, and supplements. Moreover, it’s rare that individuals are so scrupulous about avoiding sun exposure that it causes vitamin D deficiency.
Do people with darker skin need to wear sunscreen?
Yes. When the sun affects our skin, there are two levels of damage. One is immediate, which we recognize as sunburn and which mostly affects lighter-skinned individuals. Patients with darker skin who don’t get sunburned may think their skin is protected, but there’s a second kind of damage that leads to loss of elasticity and premature aging of skin, as well as DNA mutations in the cells that may ultimately cause skin cancer.
What are some of the other ways I can prevent skin cancers?
Seek the shade and avoid outdoor activities during the peak sun hours of 10:00 a.m. to 2:00 p.m. For sports enthusiasts, I recommend going out in the early morning, taking a break, and going out again later in the afternoon. You can also now buy a wide variety of UV protective clothing. Not just protective hats, which come in a variety of styles, but swim tights, swim shirts for boys, sleeves for tennis players, and more.
What are the warning signs of skin cancer?
In general, with skin cancer, we’ll see a persistent lesion that is growing and changing in shape and appearance and that bleeds without ever healing. It’s very important that people get to know their own skin and their own spots, so that when new things appear they can point them out to their primary care doctor or dermatologist. I recommend a head-to-toe screening with a dermatologist to establish a baseline for the future.
Which skin-protection websites are trustworthy?
For our organ transplant recipients (who have a 60- to 100-fold higher risk of skin cancer), we produced a downloadable booklet that’s posted on UCSF’s website — and the information in it is relevant to all patients: skincancer.ucsf.edu. The Skin Cancer Foundation also has good information. And the Environmental Protection Agency reports the UV Index on a scale of 1 to 10 by ZIP code.
