Treatment options for optic pathway gliomas

Abstract

Gliomas that affect the optic pathways are for the most part low-grade neoplasms that often, but not always, have good prognoses. Optimal treatment and management of optic pathway gliomas remains unclear and the decision hinges upon several factors including patient age, tumor location, and visual symptoms. We favor a treatment approach that is dependent on the location of tumor within anterior, chiasmal or posterior/hypothalamic visual pathways. In children who are minimally or not symptomatic, we recommend observation rather than early treatment intervention. Most of these patients will have neurofibromatosis type 1 (NF1) based on the natural history and their pilocytic astrocytoma histology. Serial magnetic resonance imaging studies and formal neuro-ophthalmology testing should enable close observation of these patients, with intervention being reserved for when tumor progression results in significant visual loss or proptosis. Chemotherapy is an accepted first line treatment, and a number of effective medications are available, although no agent has proven clearly superior. If progression is accompanied by the complete loss of vision, surgery can be utilized to help alleviate structural issues (ie, proptosis). Minimally symptomatic chiasmal or hypothalamic tumors that arise in the setting of NF1 can also be observed initially because of their favorable prognosis. Children with NF1 and chiasmal or posterior visual tumors who progress either on imaging or clinical grounds (ie, development of significant visual deficits) should be treated first with chemotherapy rather than radiation therapy to minimize the effects on the developing central nervous system. Individuals without NF1 presenting with a chiasmal or hypothalamic mass are candidates for biopsy to determine the underlying pathology of the lesion. Symptomatic patients with pilocytic astrocytoma should first receive chemotherapy. In contrast, other histologies including malignant optic pathway gliomas should be treated similar to other gliomas that occur in other locations with appropriate doses of radiation and chemotherapy.