FRIDAY, May 2, 2003 (HealthDayNews) -- When choosing a sunscreen, there's more than sunburn prevention to keep in mind, a New York City dermatologist warns.
The burning rays of the sun, called ultraviolet B (UVB) rays, are the primary cause of skin cancer, says Dr. Vincent DeLeo, associate professor of clinical dermatology at Columbia University. But new research shows that ultraviolet A (UVA) rays could also increase your risk for skin cancer, he says.
"This is an area of great controversy, but new studies say that some skin cancers could be UVA-related," DeLeo says. The reason: These rays penetrate deeper into the dermis, which is the base layer of the skin, and weaken the body's immune system, a process called immunosuppression.
This could explain why some skin cancers can appear anywhere on the body, not just where the skin has been directly exposed to the sun, DeLeo says.
DeLeo made his remarks this week at the American Academy of Dermatology's Melanoma/Skin Cancer Detection press conference in New York City, and in a subsequent interview.
This means people should seek out sunscreens that protect against UVA as well as UVB rays, something not always easy to do.
A sunscreen's sun protection factor (SPF) only measures protection from UVB rays, not UVA rays, so it's hard to know what you're getting, DeLeo says.
He cites a study that appeared last January in The Journal of Investigative Dermatology, an English Journal, in which 119 healthy, white-skinned men and women were asked to put sunscreen with an SPF of 15 on their buttocks, which had never been exposed to the sun. They were then radiated with both UVA and UVB rays.
Tests showed the protection against the UVA rays was less than half that of the UVB rays.
"The sunscreen protected against redness, but not against immunosuppression," DeLeo says.
DeLeo says trials are under way in the United States to test sunscreens that protect against UVA rays, including products that contain mexoryl and tinosorb. In the meantime, consumers must be diligent about using other methods of avoiding sun damage.
In addition to applying a sunscreen with a minimum SPF of 15, people should stay out of the summer sun between 10 a.m. and 4 p.m., wear protective clothing, and a broad brimmed hat.
"If you don't get a sunburn, it doesn't mean you're protected from an immunosuppression response," DeLeo says.
More information
The American Cancer Society has helpful information about the sun and skin cancer. The American Academy of Dermatology offers some compelling data on the dangers of tanning salons.
