Photoradiation therapy of experimental glioma

Abstract

The in vitro and in vivo antitumor effects of photoradiation with hematoporphyrin derivative (HPD) on malignant glioma were evaluated. Ethylnitrosourea induced rat glioma (KEG-1) cells, following incubation at various concentrations of HPD, were irradiated with 8×5 W fluorescent white cool lamps. Using photoradiation, it was possible to destroy glioma cells in a culture incubated for 2 hours at 5 μgml and 50 μgml of HPD in less than 35 minutes and less than 15 minutes, respectively. Glioma cells incubated for 6 hours at 5 μgml of HPD could destroy in less than 25 minutes. Photoradiation with HPD proved to be dose-dependently lethal in a culture of glioma cells. The brain tumor model was produced in Wistar King Aptekman (WKA) male rats by stereotaxic inoculation of KEG-1 glioma cells. The rats with brain tumors were given an injection of 10 mgkg of HPD intravenously 24 hours before photoradiation. For the photoradiation, light of a wave length of 514.5 nm was produced by an argon laser and was delivered through an optical fiber 400 μm in diameter. The optical fiber was inserted into the brain, through a burr hole made in the rat's skull. The tip of the optical fiber was placed on the tumor. The duration of the photoradiation was 20 minutes at 100 mW (120 joules). The median survival time of the controls was 24.0 days. That of HPD alone was 24.0 days and that of photoradiation alone 23.0 days. The median survival time of the treatment with photoradiation following HPD was 28.0 days with 16.6% increased life span and this was significantly longer than that of the controls (P=0.0048). In conclusion, photoradiation therapy with HPD may prove useful in the management of malignant brain tumors that are resistant to current methods of treatment.