Sunscreen Use During Childhood Reduces Melanoma Risk in Adulthood

Sunscreen application to infant opossums leads to 10-fold reduction in pre-melanotic lesions.

Using sunscreen before heading outside as a child could provide long term benefits into adulthood for the prevention of skin cancer.

In a study published online July 10, 2014, in Pigment Cell and Melanoma, a team of researchers used a natural animal model to investigate whether the use of sunscreen during infancy and childhood could reduce incidence of malignant melanoma in adulthood.

Scientists at the Texas Biomedical Research Institute used an OTC sun protection factor (SPF)-15 moisturizing lotion on infant gray short-tailed opossums in the study. The animals provide a promising research model on ultraviolet (UV) radiation—induced lesions due to occurrence of hyperplasia and neoplasia in neonates after UV radiation exposure without carcinogenic challenges, according to the study.

“While sunscreen is highly effective in preventing sunburn, this paradox has led some to question whether sunscreen is effective in preventing melanoma caused by ultraviolet (UV) light,” said senior author John L. VandeBerg, PhD, in a press release. “It has been suggested that sunscreen enables people to receive more UV exposure without becoming sunburned, and that increased exposure to UV light has led to an increasing incidence of melanoma.”

Three groups of neonatal opossum pups were exposed to 9 sub-erythemal doses of UVB radiation emitted from a fluorescent sunlamp. A control group of 174 pups received no lotion before exposure, a group of 289 pups received a moisturizing lotion without sunscreen, and a group of 325 pups received a lotion with SPF-15 sunscreen.

At the age of 4 months, the dorsal surface of the opossums was shaved and scored for the presence or absence of melanocytic nevi. There were no significant differences observed in the frequency of melanocytic nevi between the first 2 groups of opossums who received lotion without sunscreen.

In the third group of animals who received lotion with SPF-15 sunscreen, the frequency of melanocytic nevi was reduced 10-fold. Researchers noted that 43% of animals with melanocytic nevi as adolescents eventually progress to malignant melanoma in middle to late adulthood.

With the application of UV light in doses low enough that there was no sunburn or reddening of the skin observed, there was still found to be a significant difference in the development of lesions between opossums who received sunscreen and those that did not.

Researchers concluded that humans are naturally susceptible to UVB-induced melanoma without requiring promoters or co-carcinogens, are susceptible to melanoma induced by sub-erythemal doses of UVB, and are susceptible to the development of malignant melanoma in adulthood following an extended latency period.

The researchers suggest young children may be particularly vulnerable to UVB-induced melanoma, therefore, parents are encouraged to apply SPF-15 or higher sunscreen every time a child is exposed to sunlight.

“Based on these results, we speculate that the reason it is particularly important that sunscreens be used consistently in childhood, and especially in infancy, is because skin cells during growth are dividing much more rapidly than in adulthood, and it is during cell division that the cells are most susceptible to UV-induced damage,” VandeBerg said. “Evidence that supports this hypothesis is that melanoma is not induced in adult opossums when their shaved skin is irradiated by UV light in the absence of sunscreen.”