"Suicide" Gen Therapy for Malignant Central Nervous System Tumors

Despite development in surgical techniques, chemotherapy and radiotherapy, most malignancies of the central nervous system are still devastating tumors with a poor prognosis. For example, median survival of patients with malignant gliomas (astrocytoma, oligodendroglioma or mixed rype) is roughly 12 months and only 5 % of the patients survive more than 5 years after diagnosis. Fifty % of astrocytomas are ryped as glioblastoma multiforme, the most malignant form of glioma. Glioblastoma account for 15-23 % of all intracranial tumors and have a very poor median survival of 6 months with conventional therapy. Metastases account for 15-30 % of all intracranial neoplasm's and develop in 25 to 30 % of all cancer patients. The overall median survival time after surgery followed by radiation therapy in solitary metastatic lesions ranges from 9 to 23 months, depending on the rype of primary cancer. The prognosis in patients with multiple metastases, however, is much worse. Lepto-meningeal metastases from solid tumors are of increasing importance in neuro-oncology, because of the increasing frequency and the severe neurologic disabiliry it causes. About 0.8 to 8 % of patients with cancer develop leptomeningeal metastases and median survival in these patients after radio- and chemotherapy ranges from 7 to 24 weeks.