Sunscreen likely provides protection against skin cancer in some high-risk groups, but it is probably not broadly effective, according to a study of children that used the appearance of new moles as a marker of melanoma risk.
The study presented at the American Public Health Association (APHA) 2016 Annual Meeting in November 2016 looked at parental reports of sunscreen use and sun exposure to the number of new moles found when children were examined at the age of 15 years. They found no association between the overall number of moles and sunscreen use. Although this is not a perfect study, it is the longest study recording the appearance of new moles ever conducted.
The study involved 499 white children who were enrolled at birth or at age 6. The researchers used colorimeter studies to stratify the children by skin tone (lighter or darker). Each year, Dr. Crane and her colleagues conducted a skin examination on the children. In addition, parents completed a survey each year that asked about the frequency of sunscreen use when a child is outside for more than 15 minutes, the thickness of sunscreen application, parts of the body protected, and other measures.
The researchers looked at the association between the number of new moles and sunscreen use, after controlling for sun exposure, sunburns, waterside vacations, skin color, hair color, eye color, freckling, and the use of other sun protection. The only significant association they found was for lighter-skinned children who had at least three sunburns from 12 to 14 years of age. This group has significantly fewer moles if they used sunscreen than if they did not.
Sunscreen has long been touted as a protective measure against melanoma and sunburns, but some recent evidence has suggested otherwise. Sunscreens do a good job of blocking ultraviolet (UV)B rays, which are known to cause melanoma, but many do not block UVA rays. Although UVA radiation was long thought to produce only tans, it has recently been linked to melanoma.
Newer broad-spectrum sunscreens are available, however whether they prove to be more beneficial remains to be seen.
Study Calls Into Question Sunscreen in Melanoma Prevention. Medscape. Nov 04, 2016. Login may be required.