ABSTRACT
Photodynamic therapy (PDT) is a two-stage process, with the first stage consisting of intravenous injection of photosensitizer. Photodynamic therapy-induced cytotoxicity is thought to be due to the production of singlet oxygen. Vascular endothelium may selectively take up hematoporphyrin derivative or Photofrin within tumor stroma, is exquisitely sensitive to PDT, and tumor death by ischemic necrosis appears to be caused by vascular occlusion, partially mediated by thromboxane. Lederle Laboratories and Quadra Logic Technologies are seeking to obtain approval of PDT as an accepted modality in North America and Europe through the preparation of product license applications using Photofrin and fiberoptics for treatment of endobronchial lung cancer, esophageal cancer, and superficial bladder cancer. Superficial bladder cancer is one clinical application of PDT in which the potential for extirpation of existing bodily tumor burden has been reported. In the literature since the early 1980s, nearly 500 patients have been reported who have endobronchial lung cancer treated with PDT using either HPD or Photofrin.
