Photodynamic therapy of malignant brain tumors: clinical results of, difficulties with, questions about, and future prospects for the neurosurgical applications.

Photodynamic therapy (PDT) has been applied in a variety of oncological fields with good results. In neurosurgery, the clinical series are limited and the number of treated patients is not statistically significant. This work examines the results of PDT performed in our clinic and discusses some difficulties and causes of failure of this method in neurosurgical patients. Eight patients with malignant brain tumors underwent PDT. All had been treated previously by operation and radiation therapy and one patient had also received chemotherapy. At 24 hours after the i.v. injection of hematoporphyrin (5 mg/kg body weight), the tumor was removed as radically as possible and the residual tumor bed was exposed to either 630-nm light from an argon-dye laser or 600- to 680-nm light isolated from the emission of a quartz-halogen lamp. The type of sensitizer, the irradiation methods, and the peculiarities of glial tumors are examined as possible causes of failure. The longer survivals of some patients with glial tumors treated by PDT may make this treatment suitable when traditional therapies fail.