Skin cancer is the most common cancer in the United States. It affects up to 1 in 5 Americans, according to statistics from the American Academy of Dermatology.
Sun exposure is the single largest preventable risk factor for skin cancer. Yet many Americans don’t exercise necessary precautions to protect their skin.
“Skin cancer is a serious, potentially deadly cancer,” says Charles Yoon, MD, PhD, a surgical oncologist at Brigham and Women’s Hospital. “Many types of skin cancer are just as aggressive as colorectal, breast, or lung cancer.”
Despite the well-documented benefits of sunscreen to prevent skin cancer, like those reported in the Canadian Medical Association Journal, some people still question its importance. In part, this is because of several common misconceptions:
You’ve likely heard that you should reapply sunscreen every few hours when spending time outside. What many people don’t understand, however, is that sunscreen simply delays how quickly you’ll experience sun damage. Reapplying every few hours isn’t enough to bring your risk to zero.
Dr. Yoon uses the analogy of an oven mitt to explain sunscreen application. Wearing an oven mitt offers an extra layer of protection so that you don’t burn your hand when you pick up a hot pan. However, if you hold the hot pan for an hour, the heat will eventually go through the oven mitt and damage your hand.
Reapplying sunscreen after an hour is like switching out a fresh oven mitt. It may delay the time it takes to burn, but it doesn’t prevent damage entirely. It also doesn’t undo the hour of damage that’s already occurred. For true protection, even with sunscreen, you still need to limit your total time spent in the sun.
You may think “waterproof” sunscreen means that you can swim or sweat without any risks. However, there’s no such thing as truly waterproof sunscreen according to the Food and Drug Administration (FDA).
Sunscreens marketed as “waterproof” are only water-resistant. They may last longer in the water than other sunscreens, but they still wash off eventually. You need to reapply sunscreen more frequently when you sweat or swim.
Wearing sunscreen daily is one strategy to lower your risk of skin cancer, including melanoma and squamous cell carcinoma. Additionally, there are many other steps you can take:
Avoid sun exposure when the UV index is highest, usually between 10 a.m. and 4 p.m.
Choose a sunscreen with an SPF of 50 or higher and remember that it wears off more quickly when you sweat.
Limit direct exposure during times of high UV index to 1 hour or less, even when using sunscreen.
Talk to your doctor early if you notice any skin changes.
Visit a dermatologist annually for skin checks.
“Skin cancer is highly treatable when caught early,” says Dr. Yoon. Patients at Mass General Brigham have access to the latest skin cancer treatments, including through clinical trials. “Our team is nimble in adopting new standards of care because we’re directly involved in generating them.”