Photodynamic therapy in combination with CO₂ laser for the treatment of Bowen’s disease

Photodynamic therapy (PDT) involves the activation of a previously administered photosensitizing agent by visible light to induce tumor necrosis. Photosensitizers are topically applied in the treatment of skin tumors to avoid systemic side effects. In this study, we evaluated the feasibility and efficacy of aminolevulinic acid (ALA) as a photosensitizer (ALA-PDT) in combination with CO₂ laser in the treatment of Bowen’s disease (BD; intraepithelial squamous cell carcinoma). Twenty-two lesions from 18 patients were randomized into two groups: 11 lesions were treated with topical ALA-PDT (180 J/cm² at 100 mW/cm²) + CO₂ laser for one to three sessions. The remaining 11 lesions were treated with CO₂ laser alone, serving as control group. All patients were reviewed at ≤1-week intervals. Biopsies were taken from BD lesions prior to treatment. The initial evaluation was undertaken 1 month after treatment, and biopsies were harvested for histological evaluation. Patients who did not respond to the three sessions of treatment were referred to surgical treatment. In the ALA-PDT + CO₂ laser group, 72.73 % (8/11) of BD lesions showed complete remission, with an overall clearance of 90.91 %, and only one recurred (9 %) during follow-up. Local side effects included mild erythema, edema, erosion, and burning and/or stinging sensation. No systemic side effects were observed. In the control group, 63.63 % (7/11) of lesions had complete remission and the overall clearance was 54.55 %. However, five lesions (45.45 %) had recurrence. Local side effects included mild to moderate edema, erosion, ulceration, delayed healing, prolonged pain, and scarring. There existed a significant difference in recurrence rate between the two groups (P < 0.05). Moreover, after ALA-PDT plus CO₂ laser treatment, complete necrosis was observed in responsive lesions, and 3 months later, the atypical BD cells were replaced by normal keratinocytes. Topical ALA-PDT in combination with CO₂ laser is safe, effective, and is associated with low recurrence and reduced side effects.