INTRAOPERATIVE LASER-INDUCED PHOTODYNAMIC THERAPY IN THE TREATMENT OFEXPERIMENTAL HEPATIC-TUMORS

Objective: To examine the effect of photodynamic therapy (PDT) on expe rimental liver tumours in rats. Design: An experimental liver tumour m odel was used. Each of a group of Fats had two tumours simultaneously inoculated into its liver. The tumour located in the left hepatic robe was used for PDT, and the other one, in the median lobe, as a control . The haem precursor delta-amino laevulinic acid (ALA), at a dose of 3 0 mg/kg body weight, was injected 60 min before laser irradiation. Rat s in group I received ALA through a femoral vein. Those in group II re ceived ALA through the portal vein. Group III had an injection of ALA solution through the portal vein plus hepatic inflow occlusion. Three and 6 days after the treatment, the rats were killed, and the tumours were measured, and ultrastructural changes were examined using scannin g electron microscopy. Setting: Lund University Medical Laser Centre, Lund, Sweden. Results: The mean tumour volume of the treated tumours i ncreased by factors of 1.9, 1.5 and 1.7 in groups I, II and III, respe ctively, compared with the pretreatment baseline value. However, the m ean tumour volume in the control tumours increased by factors of 9.5, 4.3 and 4.8 in the respective groups. Under the light microscope, mark ed necrosis of the treated tumour and the surrounding liver tissue was observed. Scanning electron microscopy revealed heavy damage to the c ells and vessels in the treated tumour. Conclusion: PDT with ALA is an effective treatment modality for rat liver tumours.