A STUDY ON PHOTODYNAMIC THERAPY AND LOCAL INTERSTITIAL HYPERTHERMIA USING LOW POWER Nd: YAG LASER

-INCLUDING EXPERIMENTAL STUDIES-

Abstract

Photodynamic therapy (PDT) and local interstitial hyperthermia with low power Nd : YAG laser were carried out to nude mice in an attempt to study their therapeutic effects for further investigation. Pieces of solid tumor of human pancreatic carcinoma were subcutaneously transplanted in the backs of 28 nude mice which were 5-weeks old female. The following experimental therapies were begun 5-6 weeks after the transplantation. 1) PDT : Argon-dye laser was irradiated into a tumor with 300-400 mW for 10 minutes in 72 hours after intravenous injection of hematoporphyrin derivative (HpD) in a dose of 3 mg/kg. Histological changes detected after 7 days were coagulated necrosis and fibrosis in the tissues ranging from 30 to 50 % by the ratio of the area. 2) Local Interstitial Hyperthermia : An interstitial probe was punctured under controlling temperature near the margin of the tumor at 42°-43°c with 3W for 10-20 minutes. This therapy caused a marked amount of necrosis in the pancreatic tumors after 7 days. For the mechanism, it seems that one is the effect of both hyperthermia and low power Nd : YAG laser energy to cancer cells, and the other is a damage of tumor vessels caused secandarily by this therapy in vivo. Two patients with gastric cancer have been treated by local interstitial hyperthermia with low power Nd: YAG laser. It has proved to be very effective.