Leptomeningeal metastases: current concepts and management guidelines

Neoplastic infiltration of the meninges occurs when malignant cells gain entry into the cerebrospinal fluid (CSF). This is clinically recognized in 4% to 7% of all cancer patients. Leptomeningeal metastases may involve any part of the neural axis via tumor seeding; thus, a multitude of clinical presentations involving one or more domains exist, including the cerebral hemisphere, cranial nerves, and spinal cord and roots. The diagnosis of CSF metastases is often delayed and not appreciated until fixed neurologic deficits become evident. Adequate cytologic analysis of CSF fluid, neuroradiography of brain and spine, and an appropriate clinical context are the key element in diagnosing leptomeningeal metastases. A major challenge of treating neoplastic meningitis is the importance of treating the entire neural axis and stratifying patients in poor risk or good risk categories. Treatment is palliative and involves stabilizing neurologic status and prolonging survival. Median survival for untreated patients is 4 to 6 weeks. Treatment in a broad perspective entails radiotherapy and chemotherapy (systemic and intra-CSF). Commonly used intra-CSF chemotherapy regimens use drugs such as methotrexate, cytarabine, thiotepa, and a sustained-release liposome-encapsulated form of cytarabine (Depocyt, SkyePharma, London, UK). Patients with neoplastic meningitis usually experience a limited survival, even when treated using close adherence to evaluation algorithms and treatment protocols. In randomized controlled clinical trials using currently available intra-CSF chemotherapeutic agents, median survival in carefully selected, study-eligible groups of patients was 2 to 6 months.