Synchronized chemo-radiotherapy for brain tumors

The role of synchronization of the tumor cell cycle by the appropriate chemotherapies prior to radiation was investigated for potentiating the tumor suppressive effect of radiotherapy. In vitro studies, 48 per cent of all glioma cells was accumulated in G2 and M phases in 72 hours by the administration of vincristine (10 μg/ml), and 70 per cent of them was accumulated in 24 hours by VM-26 (1 μg/ml). In vivo studies, 20 per cent of cells was accumulated in G2 and M phases in 72 hours by i.v. administrations of combined vincristine (25 μg/kg) and ACNU (0.8 mg/kg). Vincristine (20 μg/kg) on day 1 and 2, and ACNU (1 mg/kg) on day 2 and 3 were i.v. administered concomittantly with radiation to 85 cases of malignant brain tumor patients. Among 32 glioblastoma patients, the reduction of the tumor size on CT (more than 50 per cent) and the neurological amelioration (excellent response) were obtained in 14 (43.8%) patients. The reduction of the tumor size or the neurological amelioration (good response) was obtained in 11 (34.4%) of them. Among 23 metastatic brain tumor patients, the excellent response was obtained in 11 (47.8%) and good response in 8 (34.8%) patients. By the administration of VM-26 (1 mg/kg i.v., day 1 to 3) to 20 malignant brain tumors, 30 per cent of the patients demonstrated excellent and 40 per cent of them showed good responses. The synchronized chemo-radiotherapy has shown better therapeutic effects than simple radiation in the inductory stage of treatment for malignant brain tumors. (J.P.N.)