Chemotherapy may result in objective tumor shrinkage and delay the need for radiation therapy in most patients.[22,23,38,39] Chemotherapy is also an option that may delay or avoid radiation therapy in adolescents with optic nerve pathway gliomas.[Level of evidence: 3iiDii] Chemotherapy has been shown to shrink tumors in children with hypothalamic gliomas and the diencephalic syndrome, resulting in weight gain in those who respond to treatment.
The most widely used regimens to treat tumor progression or symptomatic nonresectable, low-grade gliomas are the following:
The COG reported the results of a randomized phase III trial (COG-A9952) that treated children younger than 10 years with low-grade chiasmatic/hypothalamic gliomas using one of two regimens: carboplatin and vincristine (CV) or TPCV. The 5-year event-free survival rate was 39% ± 4% for the CV regimen and 52% ± 5% for the TPCV regimen.
Other chemotherapy approaches have been employed to treat children with progressive low-grade astrocytomas, including multiagent, platinum-based regimens [23,38,44]; [Level of evidence: 2Diii] and temozolomide.[46,47] Reported 5-year PFS rates have ranged from approximately 35% to 60% for children receiving platinum-based chemotherapy for optic pathway gliomas,[23,38] but most patients ultimately require further treatment. This is particularly true for children who initially present with hypothalamic/chiasmatic gliomas that have neuraxis dissemination.[Level of evidence: 3iiiDiii]
Among children receiving chemotherapy for optic pathway gliomas, those without NF1 have higher rates of disease progression than those with NF1, and infants have higher rates of disease progression than do children older than 1 year.[23,38,44] Whether vision is improved with chemotherapy is unclear.[49,50][Level of evidence: 3iiiC]
For children with symptomatic subependymal giant cell astrocytomas (SEGAs), agents that inhibit mTOR (e.g., everolimus and sirolimus) have been shown in small series to cause significant reductions in the size of these tumors, often eliminating the need for surgery.; [Level of evidence: 2C]; [Level of evidence: 3iiiC] A multicenter, phase III, placebo-controlled trial of 117 patients confirmed these earlier findings; 35% of the patients in the everolimus group had at least a 50% reduction in the size of the SEGA, versus no reduction in the placebo group.[Level of evidence: 1iDiv] Whether reduction in size of the mass is durable, obviating the need for future surgery, is unknown.