Evaluation of Neurofibromatosis Type 1 Associated Optic Pathway Gliomas

Abstract

Background/Aims: Optic pathway gliomas (OPGs) are low-grade gliomas histologically represented by pilocytic astrocytoma (PA) in 90% of cases, can develop from any part of the visual pathways such as optic nerve, chiasm, optic tract, or optic radiations which frequently involve the hypothalamus. OPGs account for 3–5% of childhood central nervous system (CNS) tumors and about 2% of pediatric glial lesions. OPGs are believed to be the most prevalent intracranial tumor in patients with neurofibromatosis type 1 (NF-1) and can occur in 15–20% of NF-1 cases. The aim of this study is to evaluate the clinical features and treatment response in patients diagnosed with optic glioma and NF-1.
 Methods: All cases diagnosed with OPG and received treatment in the Pediatric Oncology Department, between January 2015 to January 2021 were retrospectively evaluated. Inclusion criteria include children and adolescents with OPG aged between 0 and 18 years. The medical records (gender, age, tumor entity, tumor location) of patients, as well as their treatment history and magnetic resonance imaging (MRI) scans, were examined. The diagnosis of OPG was made clinically and radiologically by the tumor board. The recommendations of the Response Assessment in Pediatric Neuro-Oncology (RAPNO) working group were used in the diagnosis and evaluation of treatment response. Patients received intravenous chemotherapy with SIOP LGG 2004 (vincristine- carboplatin) with or without bevacizumab (10 mg/kg, started every 2 weeks), therapy or vinblastine (3 mg/m2, weekly). 
 Results: This study included 27 cases during the study period from January 2015 to January 2021. In this study there were 14 male (51.8 %) and 13 female (48.1 %) patients. The median age was 4.8 (range: 0.5–14.9) years. Biopsy was performed in three patients and the diagnosis was low-grade glioma (pilocytic astrocytoma) for all of them. Chemotherapy was administered to 22 cases in total. Twelve patients received vincristine-carboplatine, 5 patients received vincristine-carboplatin with bevacizumab and 5 patients received vinorelbine. Radiological response was evaluated in all 22 patients at 3 months MRI. No patient had a radiological complete respons, 11 patients (50%) had partial response, 2 patients (9%) presented with a progressive disease, showing an increase in measurements of 35% and 9 patients(40.9%) had stable disease at the 3-month evaluation.
 Conclusions: Systemic and visual problems play a significant role in the selection of treatment for pediatric patients with optic gliomas. An essential treatment option for improving symptoms and reducing tumor size is systemic chemotherapy. A crucial therapy option for enhancing vision is bevacizumab for the patients with NF-associated OPG.