TUESDAY, April 22, 2003 (HealthDayNews) -- It would be nice if you could just pop a pill to protect you from skin cancer.
But a new study shows the tried-but-true method of wearing sunscreen every day went a long way in warding off actinic keratoses, skin lesions caused by sun damage that signal a high risk of getting skin cancer later on.
Taking beta carotene supplements, meanwhile, did nothing to prevent the lesions.
"This study provides very rigorous documentation that daily use of an SPF 16 sunscreen will over a period of two years reduce the number of actinic keratoses," says Dr. Barbara Gilchrest, professor and chairwoman of dermatology at Boston University Medical Center. "These are a marker of sun damage and precursors to carcinomas."
The study appears in this week's Archives of Dermatology.
Researchers from the Queensland Institute of Medical Research in Australia divided 1,621 adults, aged 25 to 74, into two groups. One group applied sunscreen every morning to their head, neck, arms and hands. The other group used sunscreen at their own discretion.
Study participants were also assigned to take a 30-milligram tablet of beta carotene daily or a placebo.
Researchers found people who applied sunscreen daily had 24 percent fewer skin lesions than people who used sunscreen at their own discretion. This translates into one fewer skin lesion per person over the two-year study period.
No effect was seen among the people taking beta carotene compared to those taking a placebo tablet.
In an accompanying editorial, John L.M. Hawk of St. Thomas' Hospital in London praises the study.
"The study indicated yet again the great potential value of cutaneous sunscreen application, when undertaken conscientiously and carefully, against the now extremely well-documented ravages of sunlight," Hawk says.
Actinic keratoses, while they rarely develop into cancer, are strong predictors of future malignancies, Gilchrest says.
People who have a history of actinic keratoses have a three- to twelve-fold increased chance of developing basal cell carcinoma or squamous cell carcinomas, according to the study.
Beta carotene, an antioxidant found in many fruits and vegetables, had shown promise in preventing tumors in mice.
"Everybody would like to find an oral sunscreen because it's easier to pop a pill than put something on your skin," Gilchrest says. "But this is not the first to show beta carotene has no protective effect. We have excellent sunscreens and it's clear that they work. People should use those."
In the study, the people who used sunscreen daily were compared not to those who didn't use sunscreen, but to those who used sunscreen "at their discretion."
This is an important distinction, she says.
In Australia, there have been aggressive education campaigns about the dangers of sun exposure. As a result, Australians tend to use sunscreen relatively frequently, she says.
Gilchrest recommends everyone use sunscreen every day, not just at the beach or the pool. Most lifetime sun exposure comes from doing normal daily activities: walking to your car in a parking lot, sitting outside for lunch, gardening, to name a few.
"For most people, most of their lifetime sun exposure is in these little tiny bits," Gilchrest says. "It's not the weeks they go on vacation or go to the beach. If you really want to be careful about sun damage, you have to protect yourself every day."
More information
The Skin Cancer Foundation has more on the types of skin cancers, their detection and treatment. The American Cancer Society has details on beta carotene.
