TUMOR VESSEL DAMAGE RESULTING FROM LASER-INDUCED HYPERTHERMIA ALONE AND IN COMBINATION WITH PHOTODYNAMIC THERAPY

This study examined tumour vessel injury resulting from laser-induced hyperthermia alone and in combination with photodynamic therapy (PDT) in the treatment of rat liver tumours by means of scanning electron mi croscopy. A total of 18 Wistar rats were divided into three groups, Gr oup I (six animals) underwent hyperthermia for 15 min (15-min hyperthe rmia). Group II (six animals) underwent hyperthermia for 30 min (30-mi n hyperthermia). Group III (six animals) received the combined treatme nt of PDT and 30-min hyperthermia. For PDT, delta-amino laevulinic aci d at a dose of 60 mg/kg of body weight was intravenously administered 60 min before irradiation at 635 nm. The morphological results indicat ed that 15-min hyperthermia gave rise to an increase in permeability o f the vessels in the treated tumour. Thirty-min hyperthermia caused ex treme oedema of vascular endothelial cells and restrictive openings of tumour branch vessels. The combined therapy of PDT and hyperthermia d estroyed tumour vasculature. Large breaks of the inner wall of the tre ated tumour vessels were deeply involved in the basement membrane of t he vessel. The results indicate that there may be a close link between inhibition of tumour growth and degree of damage to tumour vessels. ( C) 1997 Elsevier Science Ireland Ltd.