[Histopathological and autoradiographical studies of experimental brain tumors after continuous local...

Continuous local chemotherapy has been evaluated as being an effective administration method and as a possible adjuvant therapy in the sensitivity aspect of the cell cycle for malignant glioma. However, neurotoxicity of anti-cancer agents in the normal brain and non-effective methods for the deeper part of the tumor seem to be the most serious problems. This study was initiated to evaluate histological findings, the uptake distribution, and neurotoxicity of the continuous local administration of isotope labeled anti-cancer agents in the brain tumor of rats. The experimental brain tumor of rats and the method of continuous local chemotherapy were as follows. The tumor was produced by intracerebral inoculation of cultured cells derived from rat brain tumor induced by Rous sarcoma virus (Kumanishi et al. strain). One week later Fluorouracil (5-6-3H) (17.7 Ci/m mol) and methotrexate (L-glutamyl 3-4-3H) (41.0 Ci/m mol) were administered into the brain tumors of rats utilizing a mini osmotic pump (Alzet Model 2001), respectively. We used five rats of various groups. The rats were sacrificed at various time intervals (6 hrs, 12 hrs, 24 hrs, 48 hrs, 72 hrs and 7 days). The tumor tissues for light microscopic autoradiography were fixed in 10% formalin for 24 hours. Sections for the light microscopic autoradiography were cut at 4 mu thick and coated with Sakura NR-M2 drips. Following exposure for one week at 4 degrees C, the sections were stained with Konidol X. Six hours after administration, slight radioactivity was distributed in the subarachnoid space and subpial brain tissue in the vicinity of the inserted tube. Twenty-four hours after administration, high radioactivity was clearly present in many tumor cells and phagocytes at the tube tip, but no radioactivity was observed in the deeper part of the tumor or normal brain tissue. In the vicinity of necrosis foci, acute toxic inflammation was also observed. In conclusion, this experimental study shows that these anti-cancer agents are capable of direct penetration into the neoplastic cells of an intracerebral tumor following continuous local administration. However, necrotic foci were small in size. The most serious side effect seemed to be the presence of acute toxic inflammation in the vicinity of the necrotic foci.