central nervous system tumor, a neoplasm of the brain or spinal cord that characteristically does not spread beyond the cerebrospinal axis, although it may be highly invasive locally and have widespread effects on body functions. Intracranial neoplasms are about four times more common than those arising in the spinal cord. From 20% to 40% of brain tumors are metastatic lesions from primary cancer elsewhere, such as in the breast, lung, GI tract, kidney, or a site of melanoma. See also brain tumor, spinal cord tumor.
