Cancer can spread to the cerebral spinal fluid (CSF) and meninges, and rarely, can originate there. When cancer involves the meninges, it causes cancerous meningitis. It has clinical similarities to infectious meningitis in that it commonly causes confusion, drowsiness, a stiff neck, and other meningeal signs, and if untreated, causes death. It is different from infectious meningitis in that the time course is somewhat slower (many days or weeks) and it more commonly tends to cause focal neurological deficits. Meningeal cancer is a devastating clinical situation; it causes severe neurological impairment, and carries a grim prognosis despite treatment. Fortunately, distressing symptoms can respond to intervention.

Meningeal cancer is fairly common. About 5% of patients with metastatic cancer will develop clinically significant cancerous meningitis, although autopsy surveys show a higher prevalence, indicating it can be asymptomatic particularly in patients who are otherwise quite ill. A peculiar feature of the epidemiology of meningeal cancer is that some kinds of malignancies have a striking predilection to metastasize to the leptomeninges, such as melanoma. About 90% of patients who die from metastatic melanoma have central nervous system metastases, and this commonly includes the meninges. Other kinds of cancer are much less likely to metastasize to the leptomeninges, such as bladder or prostate cancer. However, it can occur in any kind of cancer. About 5% of patients who die from a malignant supratentorial glioma have meningeal spread of glioma at autopsy, but only rarely is gliomatous meningitis of any clinical significance.