RESUMEN
Primary malignant glial neoplasms of the central nervous system have a dismal 2-yr prognosis. An innovative approach to these formidable lesions is photodynamic therapy that employs a chemotherapeutic photosensitizing agent in combination with wavelength specific light to produce cytotoxic reactions capable of destroying neoplastic tissues. Animal and initial clinical studies of the application of photodynamic therapy to intracranial neoplasms have been promising. Parameters to optimize the efficacy of this treatment are under investigation. A review of the preclinical and clinical studies of photodynamic therapy for intracranial neoplasms is described.
Asunto(s)
Neoplasias Encefálicas/tratamiento farmacológico , Éter de Dihematoporfirina/uso terapéutico , Fotoquimioterapia , Fármacos Fotosensibilizantes/uso terapéutico , Fototerapia , Animales , Neoplasias Encefálicas/diagnóstico por imagen , Supervivencia Celular/efectos de los fármacos , Éter de Dihematoporfirina/farmacocinética , Perros , Glioma/terapia , Derivado de la Hematoporfirina/uso terapéutico , Humanos , Radioisótopos de Indio/farmacocinética , Rayos Láser , Fármacos Fotosensibilizantes/toxicidad , Pronóstico , Cintigrafía , Células Tumorales CultivadasRESUMEN
Photodynamic therapy is being investigated as an adjuvant treatment for intracranial neoplasms. The efficacy of this therapy is based on the uptake of photosensitizer by neoplastic tissue, its clearance from surrounding brain tissue, and the timing and placement of photoactivating sources. Photofrin-II is the photosensitizer most actively being investigated. We labeled Photofrin-II with Indium-111 and studied the uptake and distribution of this agent in 20 patients with intracranial neoplasms, using single photon emission computed tomography (SPECT) with volume rendering in three dimensions. Of these patients, 16 had malignant glial tumors, 2 had metastatic deposits, 1 had a chordoma, and 1 had a meningioma. Anatomical-spatial data correlated well between the SPECT images and contrast-enhanced computed tomography or magnetic resonance images. Regions of focal uptake on SPECT images correlated with the surgical histopathological findings of the neoplasm. The kinetics of photosensitizer uptake varied according to the tumor's histological findings, the patient's use of steroids, and among patients with similar types of tumor histology. Peak ratios of target-to-nontarget tissue varied from 24 to 72 hours after injection. The study data show that, to be most effective, photodynamic therapy may need to be tailored for each patient by correlating SPECT images with anatomical data produced by computed tomography or magnetic resonance images. Photoactivating sources then can be placed, using computer-assisted stereotactics, to activate a prescribed volume of photosensitized tumor at the optimal time for treatment.