Photoradiation diagnosis and therapy. Dermatologic and photobiologic aspects

Photoradiation with photosensitizing porphyrins offers a potentially useful approach to the diagnosis and treatment of certain human cancers. The mechanism of porphyrin photosensitivity as studied in cultured cells or in the skin has been studied thoroughly. Possible targets that have been identified include membranous cellular organelles, DNA, and the plasma membrane. Mediators of the reaction include reactive oxygen species, particularly singlet oxygen, that may elicit lipid peroxidation and the activation of complement. Further research is needed to identify photosensitizers with greater selectivity for malignant cells and to develop even better sources of radiant energy.