RADT-27. FRACTIONATED RADIOTHERAPY AS FIRST-LINE TREATMENT FOR INTRACRANIAL MENINGIOMAS

Abstract BACKGROUND Meningiomas are the most common primary brain tumour, and patients requiring intervention typically undergo surgical resection as first-line therapy. However, fractionated radiotherapy (fRT) treatment remains an option for with larger tumours contraindications, although outcome prediction in this group uncertain. We aimed to assess clinical factors that contribute failure a cohort of meningiomas treated fRT METHODS Patients intracranial at our institution from November 1, 1998 December 30, 2017 were reviewed. Those who received upfront resection, radiosurgery, or had less than 6 months follow up excluded. applied logistic regression Cox analysis ascertain key predictors failure, progression-free survival (PFS), adverse events following radiotherapy. RESULTS Our included 147 tumours, which 25 progressed after (median PFS 3.45 years). Tumours RT median gross tumour volume (GTV) those did not (32.3cm3 vs 20.2cm3,p = 0.03768). Pre-RT GTV greater 11.27cm3 was independently predictive failure. Larger pre-RT also associated significant (grade 3/4) fRT. Finally, cerebellopontine angle more prevalent (20% 3.3%, p 0.0046), whereas cavernous sinus optic nerve sheath longer (p 0.0067). CONCLUSION present largest known first line therapy find location be critical outcome, adding discussion considerations heterogeneous disease.