Management of Solid Tumor CNS Metastases in Children

Pediatric solid tumor central nervous system (CNS) metastases are rare and distinct from CNS metastases from either pediatric leukemias or adult solid tumors, both of which occur at a much higher frequency. This suggests a fundamental difference between the adult and pediatric blood-brain barriers, perhaps reflecting an increased permeability to systemic treatments, or a tendency toward the use of myeloablative therapy in the pediatric population. Due to their low incidence (approximately 1–10%) in pediatric solid tumor cases, CNS metastases are not routinely screened for and typically present with neurologic symptoms and as a late finding. Treatment is often targeted to CNS symptoms and the primary tumor type, with options generally including surgery, chemotherapy (systemic, intrathecal, or intraventricular delivered through an implantable ventricular reservoir), radiation, stem cell therapy, or immunotherapy. Previous reports suggest an association between aggressive multimodal therapy and rare, long-term survival in pediatric patients with CNS metastases from multiple different primary tumor types. Certain factors have been found to be associated with the development of CNS metastases, including diagnostic lumbar punctures, the presence of pulmonary metastases, and certain subtypes of primary tumors. We thus recommend consideration of CNS screening in pediatric solid tumor patients with predisposing factors.