anaplastic brain tumorastrocytoma brain tumorpilocytic astrocytoma brain tumoranaplastic astrocytomaastrocytoma treatmentanaplastic astrocytoma glioblastomaanaplastic astrocytoma gliomamalignant anaplastic astrocytomaanaplastic astrocytoma prognosisanaplastic pilocytic astrocytomarecurrent anaplastic astrocytomarefractory anaplastic astrocytoma