Overview of Pathology and Treatment of Primary Brain Tumors

Primary brain tumors (PBTs) are a pathologically diverse group of neoplasms that remain refractory to treatment. Gliomas are neoplasms of neuroepithelial origin that comprise the largest subgroup and most commonly diagnosed form of PBT. Gliomas usually demonstrate diffuse and infiltrative growth, especially high-grade varieties such as glioblastoma multiforme, anaplastic astrocytoma, and tumors of oligodendroglial origin. Surgical resection is the initial form of therapy for most patients with a PBT. A complete resection should be attempted for all low-grade tumors. For accessible high-grade lesions, gross-total resection of all enhancing tumor and regionally infiltrated brain should be considered. External beam fractionated irradiation should be administered to all patients with high-grade gliomas and to selected patients with inaccessible or progressive low-grade PBT, especially if symptomatic or older than age 40. The standard regimen consists of 5000-6000. cGy administered in 180- to 200-cGy daily fractions over 5-7. weeks. Chemotherapy should be considered as adjunctive treatment for all malignant PBTs and for selected low-grade gliomas. Temozolomide is an alkylating agent with a broad range of activity, which is often used in combination with irradiation, as well as in the adjuvant setting, for high-grade astrocytomas. Molecular therapeutic approaches are under development and entering early clinical trials.