TOPICAL PHOTODYNAMIC THERAPY WITH ENDOGENOUS PORPHYRINS AFTER APPLICATION OF 5-AMINOLEVULINIC ACID - AN ALTERNATIVE TREATMENT MODALITY FOR SOLAR KERATOSES, SUPERFICIAL SQUAMOUS-CELL CARCINOMAS, AND BASAL-CELL CARCINOMAS

Background: Topical Photodynamic therapy with endogenous porphyrins consists of irradiation of a tumor with visible light after the application of exogenous 5-aminolevulinic acid. Objective: To assess the effectiveness of this modality, patients with precancerous conditions and various skin cancers were treated. Methods: Thirteen patients with 70 skin lesions were enrolled. Standard treatment involved the topical application of 20% 5-aminolevulinic acid in an oil-in-water emulsion. The emulsion was applied under an occlusive dressing for 4 to 8 hours before exposure to photoactivating light. Results: We observed a complete response after a single treatment for all 9 solar keratoses, 5 of 6 early invasive squamous cell carcinomas, and 36 of 37 superficial basal cell carcinomas. Only 1 of 10 noduloulcerative basal cell carcinomas completely resolved. Eight cutaneous metastases of malignant melanoma were therapeutic failures. Conclusion: Topical photodynamic therapy with endogenous porphyrins is effective for superficial epithelial skin tumors.