Photodynamic therapy of human cancer

Photodynamic therapy (PDT) is currently an investigational therapy for human cancer. PDT is performed in two steps: (a) the injection of a photosensitizer, followed by a period of time during which it is cleared from most normal tissues; and (b) activation of the photosensitizer by exposure to light. Singlet oxygen is thought to be the agent produced by photoactivation most responsible for tumor destruction. Over 3000 patients have been treated with PDT and reported in the literature. The published results of clinical PDT in the treatment of superficial bladder cancer, gynecological cancer, endobronchial malignancies, gastrointestinal cancer, intracranial cancer, ocular cancer, and cutaneous and subcutaneous cancers are critically reviewed in the present work. The current laser types used for clinical PDT are reviewed, as well as light delivery devices which have been recently developed. In situ light dosimetry devices and their use in the treatment of superficial bladder cancer and for intraoperative therapy are discussed