Photodynamic therapy.

Photodynamic therapy is an experimental method for treating malignant tumors. Injection of a tumor-localizing and photosensitizing agent and its subsequent activation by an appropriate wavelength of light can lead to tumor destruction, apparently through disruption of the vascular integrity of the neoplasm. The mechanism by which the blood vessels are destroyed appears to involve damage to the endothelium and release of vasoactive substances including thromboxane. The clinical utility has yet to be completely established, but the modality seems likely to play a role in the management of a variety of neoplasms. The diagnostic potential of this technology also appears to hold considerable promise. Advances in technological support for the clinical use of photodynamic therapy seem to hold the key to its wide clinical application.