The use of porphyrins for localization and photodynamic therapy of neoplastic disease has been the topic several international symposia reviews and books during the proceeding five years. The literature on this topic has continued to grow, as have the numbers of presentations at national and international meetings relating to photobiology, chemistry, and lasers. In this volume, it is the intention of the editor to provide both information on current research projects, and detailed methodology used in such investigation. A bibliography on the subjects of porphyrin localization and therapy in included. The manuscripts contained in this volume are based on reports given at a porphyrin Photosensitization workshop which was held in Philadelphia, July 6-7, 1984. This Workshop was supported by NIH grant CA 36746, together with funds from the Fogarty International Center. Authors were requested to update their contributions to provide a summary of progress to mid 1985.

Manuscripts containing material not presented in Philadelphia are also included, notably a series of articles describing current clinical and pre-clinical results from China. Since the Philadelphia Workshop, a meeting was held in Alghero, Sardinia (May, 1985), and additional conferences are now being planned; this attests to the continued interest in photodynamic therapy involving porphyrin in photosensitization. The successful development of this modality has required communication among a variety of workers in diverse fields. These include porphyrin chemistry, photochemistry, and photobiology, analytical chemistry, biophysics, pharmacology, surgery and medicine. While the clinical been the mingling of workers from many different disciplines, with resulting collaborations sometimes extending to unrelated topics. The use of porphyrins for tumor-localization had its beginnings in work reported by Lipson 25 years ago. This involved a collaborative effort with Dr.

Samuel Schwartz, at the Mayo Clinic, which yielded a porphyrin product termed HPD (hematoporphyrin derivative) which was then, and still remains, the most effective tumor photosensitizer known. This work was of little initial interest to the biomedical field, since appropriate instrumentation for its exploitation was not available until the development of lasers and optical fibers for light distribution. But a small group of workers continued to examine porphyrin-tumor affinity relationships, generally with little outside support. The current cascade of research projects, literature reports and conferences was initiated by a series of investigations by Dr. T.J. Dougherty, at the Roswell Park Memorial institute in Buffalo. Dougherty provided a reliable source of drug, together with information on light sources, clinical protocols, and other information to interested investigators.

A series of pioneering physicians, notably James Kennedy in Ontario, Ian Forbes in Australia, Oscar Balchum in Los Angeles, Yoshihiro Hayata in Japan, and Denis Cortese at the Mayo Clinic, provided the early effort, many of the fundamentals of porphyrin photosensitization have been reported, and guidelines for further work are clearly visible. This volume is intended to provide a reference for further studies in the field of porphyrin phototherapy, as well as a description of the current status of selected fields of research.