Caffeine could help prevent skin cancer, say scientists

CAFFEINE could be a useful addition to sunscreen, since it both absorbs ultraviolet light and protects against skin cancer, say scientists.

A study has shown how the coffee stimulant acts at the molecular level to prevent sunlight triggering tumour development in the skin.

The findings suggest that “topical application” of caffeine in creams or lotions could help prevent sun-induced skin cancer.

A number of previous studies had already shown that coffee and tea consumption reduced the risk of less serious, non-melanoma, skin cancers caused by exposure to ultraviolet (UV) rays.

In the largest investigation, involving 93,676 women, each daily cup of caffeinated coffee was dose-dependently linked to a 5% drop in skin cancer prevalence.

Decaffeinated coffee had no effect, and tea had a reduced effect consistent with its lower levels of caffeine.

The research, led by Dr Allan Conney from Rutgers University in New Jersey, tested the idea that caffeine interferes with a particular cancer-associated biological pathway.

Caffeine suppresses an enzyme, called ATR, that “rescues” stressed or DNA-damaged cells.

Mice genetically engineered to reduce the function of ATR, thus mimicking the effect of caffeine, were found to be far more prone to UV-induced skin cancer.

Inhibiting ATR appeared to force sun-damaged skin cells to die rather than become cancerous.

When mice were exposed to UV light, tumours developed three weeks later in those modified to have less active ATR.

After 19 weeks of UV exposure, the engineered mice had 69% fewer tumours than unmodified mice. They also had four times fewer invasive tumours.

The findings were published yesterday in Proceedings of the National Academy of Sciences.

Writing in the journal, the scientists said: “Combined with the extensive epidemiologic data linking caffeine intake with decreased skin cancer development, these findings suggest the possibility of topical caffeine application could be useful in preventing UV-induced skin cancers.

“An additional appealing aspect of topical application of caffeine is that it directly absorbs UV and thus also acts as a sunscreen, potentiating the efficacy of topical UV protection.

“The chemopreventive approach via ATR inhibition might be especially beneficial for individuals at high risk of UV-associated non-melanoma skin cancers.”

Professor Dot Bennett, an expert in cell biology at St George’s, University of London, said: “Interesting progress on the likely mechanism by which caffeine reduces the risk of the commonest form of skin cancer, squamous cell carcinoma (SCC).

“The authors suggest adding caffeine or related molecules to sunscreens. First, one might want to check there is no adverse effect of caffeine on the incidence of other cancers, especially melanoma, which kills over four times as many people as SCC.

“Caffeine lotion might promote tanning a little, since this family of molecules stimulates pigment cells to make more pigment.”