title: Photodynamic therapies: principles and present medical applications.
abstract: Photodynamic therapy (PDT) by porphyrins and related tetrapyrrole derivatives is an emerging new treatment modality of tumors of lung, eosophagus and skin and of age-related macular degeneration. Phase III clinical trials for other applications such as re-stenosis after angioplasty are also underway. Under systemic conditions, the transport of porphyrin photosensitizers by serum low density lipoproteins and their specific delivery to tumor cells and vasculature is a determinant of treatment effectiveness. However, this effectiveness can be improved by increasing the selectivity of the photosensitizer uptake by tumors and by using photosensitizers absorbing light in the 660-800 nm range where tissues have the highest transmittance. Another treatment showing great promise is the PDT of skin cancers after topical application of the protoporphyrin IX precursor delta-aminolevulinic acid (or its ester forms). In all the cases, the photosensitizers should be rapidly excreted to avoid a long lasting skin photosensitivity.
authors.affiliation: Clinica Universitaria de Dermatologia, Hospital de Santa Maria, Lisbon, Portugal.
authors.forename: João N
authors.initials: JN
authors.lastname: Silva
authors.forename: Paulo
authors.initials: P
authors.lastname: Filipe
authors.forename: Patrice
authors.initials: P
authors.lastname: Morlière
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Mazière
authors.forename: João P
authors.initials: JP
authors.lastname: Freitas
authors.forename: José L
authors.initials: JL
authors.lastname: Cirne de Castro
authors.forename: René
authors.initials: R
authors.lastname: Santus
mesh_terms: D000622:Aminolevulinic Acid / Q000494:pharmacology; D001913:Bowen's Disease / Q000628:therapy; D002986:Clinical Trials as Topic; D006801:Humans; D008027:Light; D008077:Lipoproteins, LDL / Q000378:metabolism; D008297:Male; D009369:Neoplasms / Q000378:metabolism; D010778:Photochemotherapy / Q000379:methods* / Q000639:trends; D017319:Photosensitizing Agents / Q000494:pharmacology; D011524:Protoporphyrins / Q000378:metabolism; D012867:Skin / Q000473:pathology; D012871:Skin Diseases / Q000628:therapy; D012878:Skin Neoplasms / Q000628:therapy
chemical_list: D008077:Lipoproteins, LDL; D017319:Photosensitizing Agents; D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX