Low-grade gliomas

Abstract

Low-grade gliomas are uncommon primary brain tumors classified as histologic grades I or II in the World Health Organization (WHO) classification. The most common variants are pilocytic and low-grade astrocytomas, oligodendrogliomas, and mixed oligo-astrocytomas located in the cerebral hemispheres. Prognostic factors that predict progression-free and overall survival include young age, pilocytic histology, good Karnofsky performance status, gross total resection, lack of enhancement on imaging, and small preoperative tumor volumes. Edema and vasogenic effects are typically managed with corticosteroids. Dexamethasone is given at an initial dosage of 4 mg given four times daily. Anticonvulsants are given prophylactically after resection and for patients who present with seizures. The rationale for open craniotomy depends on the need for immediate palliation of symptoms by reduction of intracranial pressure or focal mass effect, and/or improved oncologic control. Gross total resection of tumor is generally defined as the absence of residual enhancement on contrast-enhanced postoperative MRI scan. Most retrospective studies suggest that patients who have undergone a gross total resection of tumor have improved survival. Depending upon the proximity of the tumor to eloquent brain, gross total resection may or may not be possible. In these cases a stereotactic biopsy is required to provide the histologic diagnosis. Adjuvant radiotherapy is recommended for patients with incompletely resected grade II tumors or for patients older than age 40 regardless of extent of resection. It may be considered for any pilocytic astrocytoma from which a biopsy has been performed. Phase III randomized prospective trials have shown statistically significantly improved progression-free survival at 5 years with the addition of radiotherapy, though overall survival does not appear different. Based on prospective randomized phase III trials, 50.4 Gy to 54 Gy of conventionally fractionated radiotherapy appears to be a safe and effective regimen with minimal neurotoxicity; 45 Gy may be adequate for biopsied pilocytic astrocytomas. Currently, RTOG trial 98-02 is investigating the efficacy of postradiation PCV chemotherapy (procarbazine, CCNU, and vincristine) in the treatment of newly diagnosed unfavorable low-grade gliomas. Other areas of investigation include Temozolomide chemotherapy and the association of 1p and 19q chromosomal deletions with prolonged survival in oligodendrogliomas and sensitivity to PCV chemotherapy. Radiosurgery and/or experimental chemotherapy may provide some measure of local control in the recurrent disease setting.

High-Resolution Contrast-Enhanced, Susceptibility-Weighted MR Imaging at 3T in Patients with Brain Tumors: Correlation with Positron-Emission Tomography and Histopathologic Findings

“…18,19 Low-grade gliomas (WHO grades I and II) are amendable to (radio)surgical resection with curative intent, and adjuvant radiochemotherapy is only recommended for patients with incompletely resected grade II tumors or for patients older than age of 40 years regardless of the extent of resection. 20,21 In an effort to preoperatively differentiate between high-grade and low-grade lesions and to determine the optimal patient treatment, very often a stereotactic biopsy is performed preoperatively. 21 Burger et al 22 found that, among histopathologic features such as cell frequency, nuclear atypia and mitotic activity, necrosis, and vascular proliferation, only vascular proliferation differentially predicted both the short-and longterm survival in patients with anaplastic astrocytomas.…”

“…20,21 In an effort to preoperatively differentiate between high-grade and low-grade lesions and to determine the optimal patient treatment, very often a stereotactic biopsy is performed preoperatively. 21 Burger et al 22 found that, among histopathologic features such as cell frequency, nuclear atypia and mitotic activity, necrosis, and vascular proliferation, only vascular proliferation differentially predicted both the short-and longterm survival in patients with anaplastic astrocytomas. To date, the detection of vascular proliferations within a malignant brain lesion places a malignant brain tumor in the WHO IV classification, and, typically, pathologic microvascularity is not uniform throughout a lesion.…”

Monitoring temozolomide treatment of low-grade glioma with proton magnetic resonance spectroscopy

“…Low-grade gliomas (World Health Organisation (WHO) grade II astrocytoma, oligodendroglioma and mixed oligoastrocytoma) tend to be slow-growing tumours (Behin et al, 2003) and there remains considerable debate about the appropriate first-line treatment (Stieber, 2001;Rees, 2002). A policy of surveillance is widely accepted and active treatment in the form of surgery or radiotherapy is generally offered at the time of tumour progression.…”

Bone Marrow-Derived Cells Support Malignant Transformation of Low-Grade Glioma

“…Currently, initial treatment consists of pharmacologic seizure control if patients present with seizures and steroids for vasogenic edema (Prabhu et al, 2010, Stieber, 2001). For patients with lesions amenable to surgery, the goal is gross total resection as many studies have found overall survival to correlate with extent of initial resection irrespective of adjuvant therapy.…”