MONDAY, Dec. 6, 2010 (HealthDay News) -- Applying sunscreen every day to the head, neck, arms and hands reduced the chances of getting melanoma by half, a new study has found.
Researchers in Australia divided more than 1,600 white adults ages 25 to 75 into two groups. One group was told to apply sunscreen daily to the head, neck, hands and arms for five years between 1992 and 1996. The other group was told to use sunscreen only as often as they wished.
Researchers then kept up with the participants for the next 10 years using annual or twice-yearly questionnaires.
During that period, 11 people who used sunscreen daily were diagnosed with melanoma compared to 22 people in the "discretionary" use group, though the result was of "borderline statistical significance," according to the study.
Sunscreen also seemed to protect from invasive melanomas, which are harder to cure than superficial melanomas because they have already spread to deeper layers of the skin.
Only three people in the daily sunscreen group developed one of these invasive melanomas compared to 11 in the discretionary sunscreen group, a 73 percent difference.
"We have known for along time that sunscreen prevents squamous and basal cell carcinomas but the data on melanoma has been a little bit confusing," said Dr. Howard Kaufman, director of the Rush University Cancer Center in Chicago and a melanoma expert who was not involved with the research. "This is a well-controlled study that took into account variables such as how much time people spent in the sun. From the data, it appears wearing sunscreen does reduce the risk of melanoma."
Participants were also given 30 mg of either the nutrient beta carotene, which has been reputed to help protect from skin cancer, or a placebo. However, the study found beta carotene had no effect.
The findings are published in the Dec. 6 issue of the Journal of Oncology. Some funding was provided by L'Oreal, which makes products that include sunscreen.
Melanoma accounts for only about 5 percent of skin cancers but it causes most skin-cancer deaths, according to background information in the study. In the United States, nearly 69,000 people are diagnosed with melanoma annually and 8,600 die.
Dermatologists have long recommended sunscreen to prevent sunburn as well as basal cell and squamous cell carcinoma, which are more common types of skin cancer than melanoma, Kaufman said.
Prior research has also shown that exposure to ultraviolet rays is strongly linked to melanoma. Yet most studies on the effect of sunscreen for melanoma prevention have had problems with methodology or have been inconclusive, according to the study authors.
In the new study, participants were asked to fill out annual or twice-yearly questionnaires that asked about their time spent outdoors, their sunscreen use and previous history of skin cancer.
While no one study can offer definitive proof of a benefit, Dr. Adele Green, lead study author and acting director and professor of epidemiology at the Queensland Institute of Medical Research, said the findings do offer compelling evidence that people should wear sunscreen to ward off melanoma.
"When people are fair-skinned and are exposed to intense sunlight insummer or holidays in sunny places, it is important for adults to usesunscreen regularly along with other standard sun protection measureslike avoiding midday sun and use of protective clothing," Greene said.
Participants who were in the daily sunscreen group were more likely to continue to use sunscreen regularly than those in the discretionary group during the 10 years after the trial ended.
During the trial, researchers provided them with a broad-spectrum SPF 16 sunscreen. Those in the daily sunscreen group were less likely develop a melanoma anywhere on their bodies, not just their head and arms.
According to the study, people in the daily sunscreen group may have been more likely to apply sunscreen to their legs, torso and elsewhere.
And like other health behaviors, it's never too late to make a positive change, Kaufman said. Even those who were 60 and older who began using sunscreen daily were less likely to develop a melanoma, he noted.
The American Academy of Family Physicians has more on melanoma.