Glioneuronal tumours in childhood : Clinical picture, long-term outcome and possible new treatments

Sammanfattning: Background: Glioneuronal tumours are a subgroup of low-grade tumours of the central nervous system (CNS), often causing epilepsy. Overall survival is excellent, but data regarding long-term seizure outcome and late effects are scarce.Aims: The overall aim was to gather data about pre- and postsurgical factors of importance and long-term outcomes to improve standards of care. Another aim was to explore the expression of somatostatin receptor (SSTR) subtypes and mTOR pathway markers.Methods: This thesis, based on four population-based studies with both retrospective and cross-sectional parts, was performed through a long-term follow-up of a Swedish cohort of children with glioneuronal tumours in the Uppsala-Örebro health region. Patients were identified from the National Brain Tumour Registry and the National Epilepsy Surgery Registry. Various methods were used: reviews of hospital medical records, patient interviews, health-related quality of life (HRQoL) assessments with generic (Short Form 36version2) and disease specific (Quality of Life in Epilepsy-31) questionnaires, neuropsychological evaluations with Wechsler Intelligence Scale for Children-IV or Wechsler Adult Intelligence Test-IV and Reys Complex Figure Test and evaluation for possible depression with Hospital Anxiety Depression Scale. Immunohistochemical analyses for SSTR subtypes 1, 2a, 3 and 5 and mTOR pathway components ezrin-radixin-moesin and pS6 were performed on tumour specimens.Results: Glioneuronal tumours seem to be more frequent than previously reported, accounting for 13.5% of all childhood CNS tumours. They often cause medically refractory epilepsy resulting in cognitive impairment. Neurosurgery was often delayed; mean time from symptom debut to lesionectomy was 4.6 years. Long-term seizure freedom was achieved in 84% of patients who had a gross total resection (GTR) and is important for long-term cognitive restitution, HRQoL, educational and vocational outcomes. SSTR2a and SSTR3 expression was a frequent finding in glioneuronal tumours. Signs of mTOR pathway activation were abundant in ganglioglioma.Conclusions: A safe GTR should be striven for and considered a first-line treatment. Long-term clinical follow-up should be offered to all patients and for those with an inoperable tumour/tumour remnant causing tumour growth and/or medically refractory epilepsy, somatostatin analogues and/or mTOR inhibitors might represent a therapeutic alternative worth exploring further.