LASERS - REFLECTIONS ON THEIR EVOLUTION

A review of the past 22 years of laser applications shows that a great deal of progress has been made. It allows one to see the evolution of laser therapy, compare it with other modalities used in surgical onco logy, and identify certain program that merit clinical trial. Use of l asers in surgical oncology began with a laser knife. Tissues were divi ded and removed with the focused beam of the CO2 laser, which replaced the scalpel previously used to perform surgical procedures. Later, th e Nd:YAG laser was used in hollow visci such as the trachea and esopha gus to open obstructed passages and possibly to cure many cancers. The operating microscope was used in the larynx to remove benign and mali gnant lesions, and for obstructing lesions to provide time to treat me dical complications by reopening airway passages, and to add irradiati on and/or chemotherapy preoperatively. Many times the Nd:YAG laser was used gastroscopically to treat bleeding or obstruction. Cytoreduction by laser made surgery or chemotherapy, or both, plausible. Addition o f the sapphire tip and, later, the bare or sculptured fiber increased the variety of procedures possible with the Nd:YAG laser. Photodynamic therapy (PDT) uses various drugs that are localized in cancer cells. The cancer is then destroyed by laser emissions of the proper waveleng th. One of the problems with PDT is getting the light to the tumor. Pr eactivation is addressed in this report. The problems associated with anaerobic tumors are discussed and suggestions for clinical trials off ered. Laser hyperthermia is compared with induced hyperthermia as well as in combination with irradiation. Protocols of local laser hyperthe rmia combined with irradiation need further exploration. This review a ddresses the use of lasers in the destruction of tumor cells for bone marrow transplant and several old and new experiments used to block th e AIDS virus. Finally ongoing research is discussed, including the pre sent and future roles of lasers. (C) 1997 Wiley-Liss, Inc.