The clinical experience of medulloblastoma treatment and the significance of time sequence for development of leptomeningeal metastasis

Among patients with medulloblastoma, an unrare aggressive central nervous system (CNS) tumor found mostly in the posterior fossa, drop metastasis from primary location to anatomically lower sites including whole spinal cord is known as a potential way for tumor to spread. There were already lots of extensive discussions regarding diagnosis and treatment for such common neurologic complication in systemic cancer; however, fewer were found about medulloblastoma. This study aimed to reexamine the possible known prognostic factors, especially drop metastasis, and defined the influence of them. We retrospectively review a series of 36 patients who suffered from posterior fossa medulloblastoma and found leptomeningeal metastasis in 12 of them. Incidence, diagnosis, prognostic factors, and treatments for this common complication are discussed. The magnetic resonance images (MRI) of these patients were reviewed. The time sequence between primary surgical procedure and development of MRI evidences of drop metastasis was used for subgrouping. Log-rank test was used for survival analysis. By survival analysis, patients with late drop metastasis, defined as new radiologic evidence of leptomeningeal involvement after primary CNS procedures, were found to have significant survival difference to those with early metastasis defined as drop metastasis found at the time of diagnosis (log-rank test, p=0.0047). Further stratification of patients within this group may help in evaluation of prognosis and development of different treatment strategies.