Reduction of UV-induced skin tumours in hairless mice by topical non-steroidal anti-inflammatory drugs

Abstract

Aims: Inhibition of ultraviolet-A and -B (UVA+B) skin tumour formation by topical treatment with non-steroidal anti-inflammatory drugs (NSAIDs) was investigated in SKH-1 hairless mice. Methodology: A UV skin tumour study was designed. Group of mice were irradiated with daily doses of UVA+B for approximately 10 min per day, 5 days per week for 10 weeks. After this 10- week, there was no further UV-exposure. The integrated UV-A irradiance (280-320 nm) was 2.4 X 10⁻⁴ W/cm² and the UV-B irradiance (320-400 nm) was 1.8 X 10⁻³ W/cm². Mice were divided into 4 groups (n=20 per group). Group 1 was treated with methanol; Group 2 received 2% indomethacin in methanol; Group 3 received 2% paracetamol in methanol; Group 4 received 2% flurbiprofen in methanol. All groups received their treatment once a day, five days per week for 25 weeks. Mice were euthanized after 35 weeks. Results: The test NSAIDs in methanol were effective in reducing the incidence and size of the skin tumours induced by UVA+B, with a significantly lower average number and/or area of skin tumours observed in the NSAID-treated mice compared to the methanol control animals (P < .05). Conclusion: The results support the hypothesis that topically applied indomethacin, paracetamol, and flurbiprofen can provide protection against skin cancer, even when applied well after the skin has been exposed to the damaging effects of UV-light.