P24A RETROSPECTIVE ANALYSIS OF THE TRANSFORMATION OF LOW-GRADE GLIOMAS INTO HIGH-GRADE FROM A SINGLE INSTITUTION

INTRODUCTION: The management and timing of treatment for Low Grade Gliomas (LGG) has been a controversial topic in neuro-oncology for several years. The main aim of this report is to identify what proportion of and the time frame during which LGG will undergo malignant transformation into High-Grade Gliomas (HGG). METHOD: A retrospective analysis of a total of 86 patients from a single institution was conducted. The individual patient medical records were reviewed for date of initial diagnosis and date of recurrence as well as the initial and subsequent disease management. RESULTS: The median age at diagnosis was 41 years (IQR 29 to 51) and the male to female ratio was 47:39. Initial presenting symptoms included epilepsy (65.1%), headache (38.4%), and neurological deficit (14.0%) whereas six cases were identified incidentally. Around half (48.84%) of the patients experienced progression of the disease and required further management with the median time to progression (TTP) being 4.14 years (95% CI, 2.78 to 5.50), whereas the median follow-up time period for the entire population sample was 3.94 years (95% CI, 3.53 to 4.35 years). Univariate analysis revealed that none of the prognostic factors including age at diagnosis, tumour location and histology, gender and surgical approach reached statistical significance. Finally multivariate analysis by means of the Cox proportional hazard model identified statistically significant differences associated with gender and age at diagnosis. CONCLUSION: This study revealed that almost half of the patients diagnosed with LGG will progress to HGG and that the majority of them will do so in the first five years following the diagnosis.