Copper vapor laser and photocarcinogenesis in hairless mice

Abstract

Background and Objective Port wine stains are commonly located on UV-exposed skin areas. We therefore examined the long-term interaction between 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 conducted 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/cm2. Beam diameter was 1 mm and pulse duration 250 msec. UV irradiation of the mice was performed 4 days weekly and started the day after laser treatment. The UV simulated solar ultraviolet radiation came from one Phillips TL 12 and five Bellarium-S SA-1-12 tubes. The daily dose was 1.3 J/cm2, equivalent to 2.1 B-MED. Results No tumors appeared 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 delayed in the group treated with 1.4 W before UV irradiation (P < 0.01) compared with those receiving UV radiation only. No significant differences 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 accelerate UV-induced photocarcinogenesis, and the laser exposure did not have a malignant potential itself. © 1996 Wiley-Liss, Inc.