New approaches to and current treatment of leptomeningeal metastases.

Leptomeningeal metastases (LM), a common problem in neurooncology, occur in approximately 5% of all patients with cancer. Aside from frequent focal signs and symptoms, LM affects the entire neuraxis; therefore, staging and treatment must encompass all cerebrospinal fluid compartments. Central nervous system staging of LM includes contrast-enhanced cranial computed tomography or magnetic resonance imaging, contrast-enhanced spine magnetic resonance imaging or computed tomographic myelography, and radionuclide cerebrospinal fluid flow study. Treatment of LM includes involved-field radiotherapy of bulky or symptomatic disease and intracerebrospinal fluid drug therapy. At present, intracerebrospinal fluid drug therapy is confined to three chemotherapeutic agents (methotrexate, cytosine arabinoside, and thiotepa) and is administered in a variety of schedules by either intralumbar or intraventricular drug delivery. Although treatment of LM is palliative, with an expected median patient survival of 6 months, it often provides stabilization and protection from further neurologic deterioration in patients with LM.