Brain Metastases and Neoplastic Meningitis
Summary of Key Points
Epidemiology
• Central nervous system metastases are common, affecting as many as 25% of patients with cancer.
• Most central nervous metastases involve the brain.
• Less often, the dura, leptomeninges, skull base, or cranial nerves may be affected.
• The terms “neoplastic meningitis” and “carcinomatous meningitis” refer to the dissemination of cancer cells within the leptomeningeal space.
• The most frequent primary tumor types that give rise to brain metastases include lung cancer, melanoma, breast cancer, and renal cell carcinoma.
Diagnosis
• Brain metastases are best detected with contrast-enhanced magnetic resonance imaging.
• Metastases generally appear as enhancing, well-circumscribed lesions with or without surrounding vasogenic edema.
• Biopsy or resection may be indicated to confirm the diagnosis, particularly in a patient with a single lesion and no cancer diagnosis or no known metastatic disease.
• Neoplastic meningitis often eludes early detection; meningeal enhancement is only visible on magnetic resonance imaging in about 50% of cases, and cerebral spinal fluid cytology may be negative initially in 40% to 50% of cases.
Treatment
• The most standard treatment for brain metastases is whole-brain radiotherapy (WBRT).
• Patients with a good prognosis and a limited number of brain metastases may benefit from more aggressive therapy such as surgery (especially for a single brain metastasis) or stereotactic radiosurgery (SRS), with or without adjuvant WBRT.
• After WBRT alone, the following observations have been made:
At least 60% of symptomatic patients improve significantly.
Median survival time is typically 3 to 6 months.
One-year actuarial local control probability may be as low as 14% or as high as 71%.
