Lasers in photodynamic therapy

Photodynamic therapy has been shown to provide a reasonable alternative to other treatment modalities for patients with certain cancers, and in some cases may be the preferred treatment. Currently, photodynamic therapy is under FDA-approved clinical investigational trials in the treatment of tumors of the skin, bronchus, esophagus, bladder, head and neck, and of gynecologic and ocular tumors. Activation of a photosensitizer retained in the cancerous cells, by red light emitted from an argon-tunable dye laser system, produces a photochemical reaction that results in the selective destruction of tumor cells. Although the injected sensitizer results in patient photosensitivity lasting 4 to 8 weeks, there have been no reports of permanent side effects. This treatment can be delivered through fiberoptics--interstitially, endoscopically, retrobulbarly, and externally, and in most cases is performed under local anesthesia. Although this is a relatively new method for treatment of cancer, reports show great promise for palliation and potential cure in some cancer patients.