The claim: You’re dutiful about applying sunscreen every day, so you’re totally protected from melanoma, right? Well, not so much. A study published in Nature suggests that sunscreen alone isn’t enough to completely ward off this highly aggressive form of skin cancer.
The research: Researchers from The University of Manchester's Cancer Research UK Institute and the Institute of Cancer Research (also located in the UK) studied the effect of UV light on mice with an abnormal BRAF gene, known to increase the risk of melanoma. They found that on unprotected skin, the UV light damaged the DNA pigment cells, which increases melanoma risk. But they also found that even though applying sunscreen to the mice before exposing them to the UV light reduced the damage, it failed to completely block out rays, merely slowing the development of the melanoma rather than preventing it entirely.
What it means: If you spend time in the sun, just putting on SPF won’t keep you totally safe from melanoma down the road. “We don’t yet know why sunscreen only provides partial protection from melanoma,” says Richard Marais, director of the Cancer Research UK Manchester Institute and one of the authors of the study. “The data suggest that while sunscreen blocks most of the immediate effects of sunscreen, some UV light appears to bypass the sunscreen and induce a small amount of DNA damage, which then increases the risk of melanoma.”
The bottom line: To truly protect yourself from dangerous UV rays, you have to practice sun safety habits in addition to wearing sunscreen. Take Marais’ advice and opt for sun-protective clothing, sunglasses, and hats when you’re exposed to the sun, and by staying indoors or in the shade from 10 AM to 4 PM, when the sun is strongest.