BITHALAMIC INVOLVEMENT PREDICTS POOR OUTCOME AMONG CHILDREN WITH THALAMIC GLIAL TUMORS

Clinical features and treatment of 36 consecutive pediatric patients w ith thalamic glial tumors confirmed by histology and characterized by neuroimaging were reviewed to identify prognostic factors. The median age at diagnosis was 10 years (range 1-18 years). Twenty-four patients had low-grade tumors (juvenile pilocytic astrocytoma n = 9, fibrillar y astrocytoma n = 6, astrocytomas not otherwise specified n = 6, gangl ioglioma n = 2 and oligodendroglioma n = 1) and 12 patients had high-g rade tumors (glioblastoma multiforme n = 7, anaplastic astrocytoma n = 4 and unclassified malignant tumor n = 1). With a median follow-up of 4.3 years among survivors, estimates of 4-year progression-free survi val (PFS) and overall survival(OS) for the entire group are 28 +/- 10 and 37 +.- 10%, respectively. Low-grade tumors were associated with a significantly better dr-year PFS (36 +/- 12 vs. 0% for the high-grade group; p 0.03) and OS (52 +/- 12 vs. 0%; p < 0.001). This review ident ified that bithalamic involvement, characterized by neuroimaging, exer ted an independent and significant negative impact on PFS and OS for p atients with low-grade tumors. Estimates of 4-year PFS and OS among pa tients with low-grade bithalamic versus monothalamic tumors were 58 +/ - 15 vs. 0% and 85 +/- 11 vs. 0% (p < 0.00001), respectively. The pres ence of bithalamic involvement did not affect outcome among patients w ith high-grade tumors. Additionally, age at diagnosis, enhancement wit h neuroimaging contrast, extension beyond the thalamus and extent of s urgical resection did not correlate with overall outcome. Because trea tment approaches varied during the study period, the impact of radiati on therapy or chemotherapy could not be assessed. This contemporary, s ingle-institution series of pediatric thalamic glial tumors demonstrat es, for the first time, the statistical significance of bithalamic inv olvement as a marker of poor prognosis among patients with low-grade g lial lesions.