Anaplastic Glioma

Abstract

The treatment of anaplastic glioma (AG) varies depending on histopathology of the tumor, molecular markers, and individual patient characteristics. Maximal surgical resection is desirable for all types of AG if technically feasible, with an acceptable level of risk, and with the goal of preserving neurologic function. As opposed to the standard treatment of glioblastoma, based on a large, randomized, phase 3 trial, there is no accepted standard treatment for AG. Anaplastic astrocytoma (AA) is most often treated with radiotherapy (RT), with or without concomitant temozolomide (TMZ) and with or without adjuvant temozolomide. Rarely is AA treated with chemotherapy alone, although different treatment modalities are being evaluated in ongoing trials. The treatment of anaplastic oligodendroglioma (AO) and anaplastic oligoastrocytoma (AOA) is influenced by the 1p/19q status, as allelic co-deletion of chromosomes 1p and 19q predicts increased sensitivity to chemotherapy and prolonged survival. In contrast to the treatment of AA, carefully selected patients with AO and AOA may be treated with chemotherapy alone. Temozolomide has largely replaced PCV (procarbazine, CCNU, vincristine) as the chemotherapeutic agent for AO and AOA, largely due to greater tolerability and less potential for toxicity. However, whether temozolomide has similar efficacy to PCV has not been fully evaluated. Patients with AO and AOA with significant residual tumor after surgery, intractable seizures, and/or non co-deleted 1p/19q status are often treated with RT with or without concomitant chemotherapy and with or without adjuvant chemotherapy. There is no standard postoperative care for anaplastic ependymoma (AE). The efficacy of upfront versus delayed RT has not been evaluated. Surgery may be indicated for patients with recurrent AG. There may be benefit on overall survival, although this has not been clearly proven. Reoperation may also provide symptomatic relief and confirm the pathology, including differentiation of radiation necrosis from recurrent tumor. Confirmation of tumor grade is often important for enrollment in clinical trials, a reasonable treatment choice for patients with recurrent tumor. Treatment of recurrent AG often depends on prior treatments. Patients who have progressed after RT alone may be treated with temozolomide or PCV. Patients treated previously with chemotherapy alone may be treated with RT at time of progression. Dose-intense temozolomide, bevacizumab alone, or bevacizumab in combination with a cytotoxic agent are other treatment options. Focused radiation such as stereotactic radiosurgery has no proven role in treating recurrent AG. A number of other treatment modalities are currently under active investigation, including targeted molecular inhibitors, immunotherapies, convection enhanced delivery, and viral gene therapies. There is no standard treatment for recurrent AE. Most patients undergo re-resection followed by RT if RT was not previously given. Chemotherapy may be given, but there is no standard chemotherapeutic regimen. Ongoing trials are evaluating the role of bevicizumab and targeted molecular agents in the treatment of AE.