Comparison of red and green light in the treatment of Bowen's disease by photodynamic therapy.

BACKGROUND: A variety of protocols exist for the treatment of Bowen's disease by photodynamic therapy (PDT) using topical 5-aminolaevulinic acid (5-ALA). OBJECTIVE: To determine the optimal wavelength (red or green light) for this treatment. METHODS: A randomized comparison study of ALA-PDT using red (630 +/- 15 nm) or green (540 +/- 15 nm) light in the treatment of Bowen's disease. RESULTS: The initial clearance rate for lesions treated by red light was 94% (30 of 32) in comparison with 72% (21 of 29) for those lesions receiving green light (P = 0.002). Over the following 12 months, there were two recurrences in the red light group and seven in the green light group reducing the clearance rates to 88% and 48%, respectively. The frequency and severity of pain experienced were similar between the two treatment groups. No hyperthermia, nor significant difference in lesional temperatures, was observed between the wavelengths studied. CONCLUSION: Green light is less effective than red light, at a theoretically equivalent dose, in the treatment of Bowen's disease by topical ALA-PDT.