Over 100 types of primary brain tumor are defined by the World Health Organization (WHO), the most commonly accepted classification system (1). Only a few entities account for the bulk of the incidence while the others are rare. The incidence rate of all primary central nervous system (CNS) tumors in the United States (U.S.) is 19.3 cases per 100,000 person-years (2). An estimated 64,530 primary CNS tumors were diagnosed in the United States in 2011. Approximately 24,070 of these tumors were malignant and this subgroup represented 1.46% of all malignant cancers diagnosed in the United States (2, 3).
Although relatively uncommon, primary brain tumors cause a disproportionate amount of morbidity and mortality, with an estimated 14,080 deaths attributed to malignant primary CNS tumors in the United States in 2013 (2). In this chapter we discuss the clinical evaluation of a patient with a suspected primary brain tumor and review the most common adult primary brain tumors encountered by oncologists: gliomas, primary central nervous system lymphomas, and meningiomas.
Patients with primary brain tumors can present suddenly with seizures or subacutely with progressive focal or non-focal neurological symptoms over several weeks to several months. Progressive focal neurological deficits are usually referable to growth of a tumor in a specific brain location. Non-focal symptoms include headache, vomiting, fatigue, cognitive changes, mood disturbances, imbalance, and gait disorder. Less often, patients may present with an acute stroke-like neurological deficit caused by hemorrhage into a previously subclinical tumor.
Headaches result from local irritation of pain-sensitive dura or from increased intracranial pressure (ICP). Headaches from increased ICP due to tumors are usually holocephalic, progressive, often associated with nausea, worse with recumbency, and may awaken a patient from sleep. They may be precipitated by Valsalva maneuvers or coughing. Systemic symptoms such as malaise, anorexia, weight loss, and fever are usually absent, and presence of these symptoms suggests a metastatic rather than primary brain tumor.
Primary brain tumors are not associated with serologic abnormalities, and no widely accepted primary brain tumor-specific systemic marker exists. Lumbar puncture (LP) for cerebrospinal fluid (CSF) analysis is indicated if there is suspicion of CNS metastasis of systemic cancers or leptomeningeal spread of astrocytoma and for staging of certain primary brain tumors that commonly disseminate in the CSF compartment such as primary CNS lymphoma and primitive neuroectodermal tumor. The CSF may demonstrate an elevated protein level and a mild lymphocytic pleocytosis. A lumbar puncture may precipitate brain herniation if there is increased ICP, and therefore should be performed only after reviewing cranial imaging and obtaining neurological consultation.
The diagnosis of a primary brain tumor is suggested by contrast-enhanced cranial imaging with either computerized tomography (CT) or magnetic resonance imaging (MRI). ...