005 Topical photodynamic therapy in dermatology – 3 years experience at Beaumont Hospital

Topical photodynamic therapy (PDT) involves selective photosensitization of a target tissue by means of a topical agent, which is then activated by light to effect an oxygen dependent cytotoxic reaction. Premalignant and malignant skin conditions including actinic keratosis, squamous cell carcinoma in situ (Bowen's disease), and superficial basal cell carcinoma (BCC) have been effectively treated with PDT. A number of studies support the use of topical PDT in the treatment of acne, warts, psoriasis and T-cell lymphoma. There are many case reports and small series, with varying results, in a wide variety of other non-malignant applications. We report our experience of topical PDT over a 3 year period. We selected patients to participate in an open study of ALA-PDT on the basis of failure of, or unsuitability for conventional therapy. One hundred and ten patients participated in the study, with a mean age of 73 years. One hundred and twenty-nine lesions were treated, which consisted of 95 lesions of Bowen's disease, 21 superficial BCC's, nine patients with multiple actinic keratosis and four with porokeratosis. Patients were assessed at 3, 6 and 12 month intervals. Clearance and recurrence rules, adverse events and patient preference (where lesions had been treated previously) were recorded, Clearance rates for actinic keratosis, Bowen's disease and BCC were 87.5%, 84%, and 57%, respectively. Seventy-four percent of patients had a single treatment. Fourteen percent had two, and the remainder had up to four treatements in total. Though topical PDT has not proven to be superior to conventional methods, it is well tolerated with excellent cosmetic results. It is of particular value in the treatment of large lesions, in those with poorly vascularised skin, and in areas of diffuse actinic damage. Careful patient selection, prior debulking of lesions, and newer more selective agents with enhanced penetration, promise to further improve outcome.