Long-term Follow-up and Histological Changes of Superficial Nonmelanoma Skin Cancers Treated With Topical δ-Aminolevulinic Acid Photodynamic Therapy

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Abstract
THE INCREASING incidence of nonmelanoma skin cancers, ie, basal cell carcinomas (BCC) and squamous cell carcinomas (SCC), has led to the search for new therapeutic modalities. Photodynamic therapy with topically applied δ-aminolevulinic acid (ALA-PDT) is a novel form of therapy for neoplasms of the skin and other organs. The principle of ALA-PDT is that topically applied ALA is metabolized by the tumor cells into photosensitizing concentrations of endogenous porphyrins, particularly protoporphyrin IX. Irradiation with visible light then leads to the selective destruction of tumor tissue.1,2 Therapy with ALA-PDT is effective for superficial nonmelanoma skin tumors, and high primary clinical response rates with excellent cosmetic results have been reported.1,3-5 Although ALA-PDT is used today experimentally in many centers around the world,6 most clinical studies of ALA-PDT of skin tumors have involved only a small number of cases and a clinical follow-up of only a few months. In the present study, we evaluated primary tumor responses and recurrence rates in a long-term follow-up (to 60 months) of 47 patients, with a total of 95 superficial BCC and 35 superficial SCC, who were treated with topical ALA and light of different wave bands.