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?

Abstract

Topical photodynamic therapy with endogenous porphyrins consists of irradiation of a tumor with visible light after the application of exogenous 5-aminolevulinic acid. To assess the effectiveness of this modality, patients with precancerous conditions and various skin cancers were treated. 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. 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 nodulo-ulcerative basal cell carcinomas completely resolved. Eight cutaneous metastases of malignant melanoma were therapeutic failures. Topical photodynamic therapy with endogenous porphyrins is effective for superficial epithelial skin tumors.