Principal Investigator Christin Burd, of the Comprehensive Cancer Center at Ohio State University, and colleagues reached their conclusion by testing sunscreen on a genetically engineered mouse model of melanoma.
While their results may appear obvious at first glance, the study authors point out that previous research has only been able to test whether sunscreen use protects against sunburn, not whether it protects against cancer.
“Sunscreens are known to prevent skin from burning when exposed to UV [ultraviolet] sunlight, which is a major risk factor for melanoma,” notes Burd.
“However, it has not been possible to test whether sunscreens prevent melanoma, because these are generally manufactured as cosmetics and tested in human volunteers or synthetic skin models.”
In a previous study, Burd and colleagues revealed how they developed a mouse model that is genetically engineered to spontaneously develop melanoma around 26 weeks after skin application of the chemical 4-hydroxytamoxifen (4OHT).
SPF30 sunscreen delayed melanoma onset, reduced tumor incidence
For this latest study, the team exposed the melanoma mouse models to UVB radiation, which is the primary cause of sunburn. UVB radiation tends to damage the epidermis – the outer layers of skin.
One day after applying 4OHT to the skin of the mice, the researchers exposed the rodents to a single dose of UVB radiation. They found this accelerated melanoma progression and the mice developed significantly more tumors.
“Melanoma-free survival was reduced by 80%, to about 5 weeks,” notes Burd.
Next, the researchers applied a variety of SPF30 (sun protection factor 30) sunscreens – all of which contained a number of UV-blocking agents – to the skin of melanoma mouse models prior to UVB exposure.
Every sunscreen applied was found to delay melanoma onset and reduce tumor development, though there were some minor differences in the melanoma-preventing abilities of each product.
“However, we later discovered that even though the sunscreens were all marketed as SPF30, some were actually predicted to have a higher rating,” says Burd. “For this reason, it is hard to compare the melanoma-preventing capacity of the different sunscreens at this time.”