Chemotherapy of low-grade gliomas

Histologic subtypes of low-grade gliomas include pilocytic astrocytomas (World Health Organization [WHO] grade I), diffuse infiltrating astrocytomas, oligodendrogliomas, and mixed oligo-astrocytomas (WHO grade II). Although extended survival is typical with these tumors, most patients eventually succumb to recurrent or progressive disease despite receiving either adjuvant radiation therapy or radiation at the time of recurrence. Not surprisingly, chemotherapy for low-grade gliomas has primarily been evaluated in the salvage setting of postradiotherapy progression in both adults and children. Unfortunately, the published body of literature describing chemotherapy for these tumors is small and subject to a number of confounding methodologic limitations. Nonetheless, some guidelines for the use of chemotherapy in these patients can be inferred from the published experience. The data reviewed clearly identifies a potential benefit for PCV chemotherapy (procarbazine, CCNU, and vincristine) in at least a subset of patients with low-grade oligodendroglial tumors. Nitrosoureas and platinum agents appear to have modest efficacy in recurrent oligodendroglial tumors and in some patients with newly diagnosed or progressive low-grade astrocytomas; however, surgery and radiation remain the primary treatment modalities for this group of malignancies. Until new data becomes available, chemotherapy still should be used only as a salvage option in previously irradiated patients with recurrent or progressive low-grade gliomas.