COPPER-VAPOR LASER AND PHOTOCARCINOGENESIS IN HAIRLESS MICE

Background and Objective: Port wine stains are commonly located on UV- exposed skin areas. We therefore examined the longterm interaction bet ween UV radiation and copper vapor laser light (578 nm, yellow light) and whether the thermal influence from laser light had a carcinogenic potential itself. Study Design/Materials and Methods: The study was co nducted in lightly pigmented hairless hr/hr C3H/Tif mice and included 8 groups of 17-20 mice. Intensities of 0.5, 1.0, and 1.4 W were used, corresponding to calibrated Hexascan fluences of 15.9, 31.8, and 44.6 J/cm(2). Beam diameter was 1 mm and pulse duration 250 msec. UV irradi ation of the mice was performed 4 days weekly and started the day afte r laser treatment. The UV simulated solar ultraviolet radiation came f rom one Phillips TL 12 and five Bellarium-S SA-1-12 tubes. The daily d ose was 1.3 J/cm(2), equivalent to 2.1 B-MED. Results: No tumors appea red in groups receiving laser light only. The time to first (P < 0.01) , second (P < 0.01), and third (P < 0.02) tumor was significantly dela yed in the group treated with 1.4 W before UV irradiation (P < 0.01) c ompared with those receiving UV radiation only. No significant differe nces could be demonstrated for the groups treated with 0.5 and 1.0 W. Conclusion: One laser treatment with the copper vapor laser did not ac celerate UV-induced photocarcinogenesis, and the laser exposure did no t have a malignant potential itself. (C) 1996 Wiley-Liss, Inc.