5-Iodo-2-deoxyuridine administered into the lateral cerebral ventricle as a radiosensitizer in the treatment of disseminated glioma.

A rat brain tumor model (Fischer 344 rats) with the clinical and pathological features of dissemination via the cerebrospinal fluid (CSF) pathways was used to demonstrate the efficacy of 5-iodo-2-deoxyuridine (IUDR) as a radiosensitizer when it is administered directly into the CSF. Stereotaxic implantation of 9L gliosarcoma cells (5 X 10(5) into the CSF of the lateral cerebral ventricle resulted in widespread dissemination and median survival of 18.5 and 20 days (range, 10-22) in two experiments. A continuous 7-day infusion of IUDR into the CSF starting on the day of tumor implantation did not provide any beneficial effect. Irradiation of the cranial spinal axis with 800 rad on days 4, 6, and 7 after implantation achieved an increase in survival time that was modest but statistically significant. However, the combination of IUDR infusion and radiotherapy resulted in marked improvement in survival time and a 10% cure rate (two of 20 rats). This is the first demonstration in vivo that IUDR administered into the CSF can be a potent radiosensitizer.