Comparison of the efficacy of ALA-PDT using an excimer-dye laser (630 nm) and a metal-halide lamp (600 to 740 nm) for treatment of Bowen's disease

Summary Background/Purpose Topical 5‐aminolevulinic acid‐based photodynamic therapy (ALA‐PDT) is an effective treatment for Bowen's disease (BD). In order to compare the efficacy of two different light sources, using either an excimer‐dye laser (EDL) (630 nm) or a metal‐halide lamp (MHL) (600 to 740 nm) a protocol for topical ALA‐PDT for treatment of BD of the extremities was established, and responses during 12 months follow‐up were assessed. Methods From 25 patients a total of 26 lesions that had been histopathologically diagnosed as BD from 2005 to 2010 in the Department of Dermatology at the Aichi Medical University Hospital were randomly selected. The light source used for the topical ALA‐PDT was EDL in 17 lesions and MHL in 9 lesions. The photosensitizing protoporphyrin IX that is produced within BD lesions 4 h after application of 20% ALA cream was mostly consumed after exposure to 100 J/cm2 irradiation using 630 nm EDL. Each lesion was irradiated once a week for 3 weeks, for a total dosage of 300 J/cm2 (100 mW/cm2). Patients were followed up clinically every 3 months for 12 months, and at 1 month after the final treatment lesions were evaluated histopathologically. Results Histologically, the complete response (CR) rate at 1‐month follow‐up was 82% (14/17 lesions) in the EDL treatment group and 100% (9/9 lesions) in the MHL treatment group (P > 0.05). The recurrence rate at 12 months after PDT was 46% (6/13 lesions, one patient lost to follow‐up) in the EDL group and 0% in the MHL group (P