SPF30 sunscreens may delay onset of skin cancer

Application of sunscreen with a sun protection factor 30 (SPF30) prior to exposure to sunlight may delay the onset of skin cancer, a new study has claimed.
The findings of the study conducted on mice can be used to identify new, more effective melanoma-preventing agents, researchers said.
"Sunscreens are known to prevent skin from burning when exposed to ultraviolet (UV) sunlight, which is a major risk factor for melanoma," said Christin Burd from Ohio State University.
"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," said Burd.

"We have developed a mouse model that allows us to test the ability of a sunscreen to not only prevent burns but also to prevent melanoma," he added.
Researchers hope that this model will lead to breakthroughs in melanoma prevention.

For the study, researchers found that if they exposed the genetically engineered mice to a single dose of ultraviolet-B (UVB) light one day after applying 4-hydroxytamoxifen (4OHT) to the skin, melanomas appeared much more rapidly, and there were many more tumours.
"Melanoma-free survival was reduced by 80 per cent, to about five weeks," said Burd.
Researchers then used the mouse model to test the ability of a number of sunscreens labelled SPF30 to prevent melanoma.

The sunscreens, which contained a range of UV-blocking agents, were applied to the mice prior to exposure to the UVB light.
All the sunscreens delayed melanoma onset and reduced tumour incidence, researchers said.