Advances in brain tumor chemosensitivity.

Despite advances in surgery and radiation, most malignant central nervous system tumours recur. Chemotherapy has assumed an important role in treatment, particularly for responsive tumors such as primary central nervous system lymphoma and oligodendrogliomas. The design of sound chemotherapeutic trials for brain tumors requires an understanding of drug resistance. Drug sensitivity may be improved in a variety of ways: through the use of agents at higher than conventional doses or in new treatment schedules, through the use of localized resistance to modulators, and even through genetic manipulation of malignant cells. As treatment with chemotherapy for central nervous system tumors becomes more successful, new measurements of tumor response may need to be developed to replace or complement standard criteria.