Glioblastoma Multiforme

Practice Essentials

Glioblastoma multiforme (GBM) is the most common and most malignant of the glial tumors. See the image below.

View Image

Histopathologic slide demonstrating a glioblastoma multiforme (GBM).

See Brain Lesions: 9 Cases to Test Your Management Skills, a Critical Images slideshow, to review cases including meningiomas, glioblastomas and craniopharyngiomas, and to determine the best treatment options based on the case history and images.

Signs and symptoms

The clinical history of a patient with glioblastoma multiforme (GBM) is usually short (< 3 months in > 50% of patients). Common presenting symptoms include the following:

• Slowly progressive neurologic deficit, usually motor weakness
• Headache
• Generalized symptoms of increased intracranial pressure, including headaches, nausea and vomiting, and cognitive impairment
• Seizures

Neurologic symptoms and signs can be either general or focal and reflect the location of the tumor, as follows:

• General symptoms: Headaches, nausea and vomiting, personality changes, and slowing of cognitive function
• Focal signs: Hemiparesis, sensory loss, visual loss, aphasia, and others

The etiology of GBM is unknown in most cases. Suggested causes include the following:

• Genetic factors
• Cell phone use (controversial)
• Head injury, N-nitroso compounds, occupational hazards, electromagnetic field exposure (all inconclusive)^[1]

See Presentation for more detail.

Diagnosis

No specific laboratory studies are helpful in diagnosing GBM. Tumor genetics are useful for predicting response to adjuvant therapy.

Imaging studies of the brain are essential for making the diagnosis, including the following:

• Computed tomography
• Magnetic resonance imaging, with and without contrast (study of choice)
• Positron emission tomography
• Magnetic resonance spectroscopy
• Cerebral angiography is not necessary

Other diagnostic measures that may be considered include the following:

• Electroencephalography: May show suggestive findings, but findings specific for GBM will not be observed
• Lumbar puncture (generally contraindicated but occasionally necessary for ruling out lymphoma)
• Cerebrospinal fluid studies do not significantly facilitate specific diagnosis of GBM

In most cases, complete staging is neither practical nor possible. These tumors do not have clearly defined margins; they tend to invade locally and spread along white matter pathways, creating the appearance of multiple GBMs or multicentric gliomas on imaging studies.

See Workup for more detail.

Management

No current treatment is curative. Standard treatment consists of the following:

• Maximal safe surgical resection, radiotherapy, and concomitant and adjuvant chemotherapy with temozolomide^{[2, 3]}
• Patients older than 70 years: Less aggressive therapy is sometimes considered, using radiation or temozolomide alone^{[4, 5, 6]}

Key points regarding radiotherapy for GBM include the following:^{[7, 8]}

• The addition of radiotherapy to surgery increases survival.^{[9, 10]}
• The responsiveness of GBM to radiotherapy varies.
• Interstitial brachytherapy is of limited use and is rarely used.
• Radiosensitizers, such as newer chemotherapeutic agents,^[11] targeted molecular agents,^{[12, 13]} and antiangiogenic agents^[13] may increase the therapeutic effect of radiotherapy.^[14]
• Radiotherapy and/or radiosurgery for recurrent GBM is controversial.

The optimal chemotherapeutic regimen for GBM is not yet defined, but adjuvant chemotherapy appears to yield a significant survival benefit in more than 25% of patients.^{[15, 1, 16, 17, 18, 19]}

Agents used include the following:

• Temozolomide
• Nitrosoureas (eg, carmustine [BCNU])
• Inhibitors of MGMT (eg, O6-benzylguanine)
• Cisplatin
• Bevacizumab (alone or with irinotecan) for recurrent glioma
• Tyrosine kinase inhibitors (eg, gefitinib, erlotinib)
• Investigational therapies (eg, gene therapy, peptide and dendritic cell vaccines, synthetic chlorotoxins, radiolabeled drugs and antibodies)^{[20, 21, 22, 23, 24, 25]}

Surgical options include gross total resection (better survival), subtotal resection, and biopsy. Because GBM cannot be cured surgically, the surgical goals are as follows:

• To establish a pathologic diagnosis
• To relieve any mass effect
• If possible, to achieve a gross total resection to facilitate adjuvant therapy^[26]

In some cases, stereotactic biopsy is followed by radiation therapy (eg, for patients with a tumor located in an eloquent area of the brain, patients whose tumors have minimal mass effect, and patients in poor medical condition who cannot undergo general anesthesia). The extent of surgery (biopsy vs resection) has been shown in a number of studies to affect length of survival. 

See Treatment and Medication for more detail.

For patient education resources, see the Cancer Center as well as the patient education article Brain Cancer.

• References

Background

Glioblastoma multiforme (GBM) is by far the most common and most malignant of the glial tumors. Attention has been drawn to this form of brain cancer by the deaths of Senator Ted Kennedy and Senator John McCain from glioblastoma.

Of the estimated 17,000 primary brain tumors diagnosed in the United States each year, approximately 60% are gliomas. Gliomas comprise a heterogeneous group of neoplasms that differ in location within the central nervous system, in age and sex distribution, in growth potential, in extent of invasiveness, in morphological features, in tendency for progression, and in response to treatments.

See images below.

View Image

A T1-weighted axial MRI without intravenous contrast. This image demonstrates a hemorrhagic multicentric tumor (glioblastoma multiforme [GBM]) in the ....

View Image

A T1-weighted sagittal MRI with intravenous contrast in a patient with glioblastoma multiforme (GBM).

Composed of a heterogeneous mixture of poorly differentiated neoplastic astrocytes, glioblastomas primarily affect adults, and they are located preferentially in the cerebral hemispheres. Much less commonly, glioblastoma multiforme can affect the brainstem (especially in children) and the spinal cord. These tumors may develop from lower-grade astrocytomas (World Health Organization [WHO] grade II) or anaplastic astrocytomas (WHO grade III), but more frequently they manifest de novo, without any evidence of a less malignant precursor lesion. The treatment of glioblastomas is palliative and includes surgery, radiotherapy, and chemotherapy.^{[27, 28, 29]}

• References

Pathophysiology

Glioblastomas can be classified as primary or secondary. Primary glioblastoma multiforme accounts for the vast majority of cases (60%) in adults older than 50 years. These tumors manifest de novo (ie, without clinical or histopathologic evidence of a preexisting, less-malignant precursor lesion), and patients presenting after a short clinical history, usually less than 3 months.

Secondary glioblastoma multiformes (40%) typically develop in younger patients (< 45 y) through malignant progression from a low-grade astrocytoma (WHO grade II) or anaplastic astrocytoma (WHO grade III). The time required for this progression varies considerably, ranging from less than 1 year to more than 10 years, with a mean interval of 4-5 years. Increasing evidence indicates that primary and secondary glioblastomas constitute distinct disease entities that evolve through different genetic pathways, affect patients at different ages, and differ in response to some of the present therapies. Of all the astrocytic neoplasms, glioblastomas contain the greatest number of genetic changes, which, in most cases, result from the accumulation of multiple mutations.

Over the past decade, the concept of different genetic pathways leading to the common phenotypic endpoint (ie, glioblastoma multiforme) has gained general acceptance. Genetically, primary and secondary glioblastomas show little overlap and constitute different disease entities. Studies are beginning to assess the prognoses associated with different mutations. Some of the more common genetic abnormalities are described as follows:

• Loss of heterozygosity (LOH): LOH on chromosome arm 10q is the most frequent gene alteration for both primary and secondary glioblastomas; it occurs in 60-90% of cases.^[30] This mutation appears to be specific for glioblastoma multiforme and is found rarely in other tumor grades. This mutation is associated with poor survival. LOH at 10q plus 1 or 2 of the additional gene mutations appear to be frequent alterations and are most likely major players in the development of glioblastomas.^[31]
• p53: Mutations in p53, a tumor suppressor gene, were among the first genetic alterations identified in astrocytic brain tumors. The p53 gene appears to be deleted or altered in approximately 25-40% of all glioblastoma multiformes, more commonly in secondary glioblastoma multiformes.^[32] The p53 immunoreactivity also appears to be associated with tumors that arise in younger patients.
• Epidermal growth factor receptor (EGFR) gene: The EGFR gene is involved in the control of cell proliferation. Multiple genetic mutations are apparent, including both overexpression of the receptor as well as rearrangements that result in truncated isoforms.^[33] However, all the clinically relevant mutations appear to contain the same phenotype leading to increased activity. These tumors typically show a simultaneous loss of chromosome 10 but rarely a concurrent p53 mutation. Overexpression or activation mutations in this gene are more common in primary glioblastoma, with mutations appearing in 40-50% of these tumors. One such common variant, EGFRvIII, has shown promise as a target for kinase inhibitors, immunotoxins, and peptide vaccines.^[34]
• MDM2: Amplification or overexpression of MDM2 constitutes an alternative mechanism to escape from p53-regulated control of cell growth by binding to p53 and blunting its activity. Overexpression of MDM2 is the second most common gene mutation in glioblastoma multiformes and is observed in 10-15% of patients. Some studies show that this mutation has been associated with a poor prognosis.^[35]
• Platelet-derived growth factor–alpha (PDGF-alpha) gene: The PDGF gene acts as a major mitogen for glial cells by binding to the PDGF receptor (PDGFR). Amplification or overexpression of PDGFR is typical (60%) in the pathway leading to secondary glioblastomas.
• PTEN: PTEN (also known as MMAC and TEP1) encodes a tyrosine phosphatase located at band 10q23.3. The function of PTEN as a cellular phosphatase, turning off signaling pathways, is consistent with possible tumor-suppression action. When phosphatase activity is lost because of genetic mutation, signaling pathways can become activated constitutively, resulting in aberrant proliferation. PTEN mutations have been found in as many as 20% of glioblastomas, more commonly in primary glioblastoma multiformes.^[36]

Eckel-Passow and colleagues classified gliomas into groups on the basis of three tumor markers: mutations in the TERT promoter, mutations in IDH, and codeletion of chromosome arms 1p and 19q (1p/19q codeletion). The groups had different ages at onset, overall survival, and associations with germline variants, which implies that they are characterized by distinct mechanisms of pathogenesis. Findings included the following^[37] :

• Among patients with a histopathologic diagnosis of glioblastoma, those with both TERT and IDH mutations had poor overall survival
• Isolated IDH mutations were significantly more frequent in younger patients (mean age at diagnosis, 37 years) and seemed to be associated with tumor evolution along a secondary glioblastoma pathway
• Mean age at diagnosis was highest (59 years) in patients whose tumors harbored TERT mutations only
• Patients whose tumors harbored TERT mutations suffered worse overall survival compared with the other molecular subgroups
• Patients with triple-negative gliomas (IDH-, TERT -, 1p19q intact) had poorer overall survival than patients who had gliomas with TERT or IDH, or who had triple-positive gliomas

Less frequent but more malignant mutations in glioblastomas include the following:

• MMAC1-E1 - A gene involved in the progression of gliomas to their most malignant form
• MAGE-E1 - A glioma-specific member of the MAGE family that is expressed at up to 15-fold higher levels in glioblastoma multiformes than in normal astrocytes
• NRP/B - A nuclear-restricted protein/brain, which is expressed in neurons but not in astrocytes (NRP/B mutants are found in glioblastoma cells.)

Additional genetic alterations in primary glioblastomas include p16 deletions (30-40%), p16INK4A, and retinoblastoma (RB) gene protein alterations. Progression of secondary glioblastomas often includes LOH at chromosome arm 19q (50%), RB protein alterations (25%), PTEN mutations (5%), deleted-in-colorectal-carcinoma gene (DCC) gene loss of expression (50%), and LOH at 10q.

Glioblastoma multiformes occur most often in the subcortical white matter of the cerebral hemispheres. In a series of 987 glioblastomas from University Hospital Zurich, the most frequently affected sites were the temporal (31%), parietal (24%), frontal (23%), and occipital (16%) lobes.^[38] Combined frontotemporal location is particularly typical.

Tumor infiltration often extends into the adjacent cortex or the basal ganglia. When a tumor in the frontal cortex spreads across the corpus callosum into the contralateral hemisphere, it creates the appearance of a bilateral symmetric lesion, hence the term butterfly glioma. Sites for glioblastomas that are much less common are the brainstem (which often is found in affected children), the cerebellum, and the spinal cord.

• References

Etiology

The etiology of glioblastoma remains unknown in most cases. Familial gliomas account for approximately 5% of malignant gliomas, and less than 1% of gliomas are associated with a known genetic syndrome (eg, neurofibromatosis, Turcot syndrome, or Li-Fraumeni syndrome).^[1]

Although concerns have been raised regarding cell phone use as a potential risk factor for development of gliomas, study results have been inconsistent, and this possibility remains controversial. The largest studies have not supported cell phone use as a cancer risk factor.^{[39, 2, 3, 4, 5, 6]}  

Studies of association with head injury, N-nitroso compounds, occupational hazards, and electromagnetic field exposure have been inconclusive.^[39]

• References

Epidemiology

Overall incidence is very similar among countries. Glioblastoma multiformes are slightly more common in the United States, Scandinavia, and Israel than in Asia. This may reflect differences in genetics, diagnosis and the healthcare system, and reporting practices. Glioblastoma multiforme is the most frequent primary brain tumor, accounting for approximately 12-15% of all intracranial neoplasms and 50-60% of all astrocytic tumors. In most European and North American countries, incidence is approximately 2-3 new cases per 100,000 people per year.

Within the United States, glioblastoma multiforme is slightly more common in whites.

In a review of 1003 glioblastoma biopsies from the University Hospital Zurich,^[40]  males had a slight preponderance over females, with a male-to-female ratio of 3:2.

Glioblastoma multiforme may manifest in persons of any age, but it affects adults preferentially, with a peak incidence at 45-70 years. In the series from University Hospital Zurich (a review of 1003 glioblastoma biopsies), 70% of patients were in this age group, with a mean age of 53 years.^[40]  In a series reported by Dohrman (1976), only 8.8% of glioblastoma multiformes occurred in children.^[41]

• References

Prognosis

Only modest advancements in the treatment of glioblastoma have occurred in the past 25 years. Although current therapies remain palliative, they have been shown to prolong quality survival. Mean survival is inversely correlated with age, which may reflect exclusion of older patients from clinical trials. Without therapy, patients with glioblastoma multiformes uniformly die within 3 months. Patients treated with optimal therapy, including surgical resection, radiation therapy, and chemotherapy, have a median survival of approximately 12 months, with fewer than 25% of patients surviving up to 2 years and fewer than 10% of patients surviving up to 5 years. Whether the prognosis of patients with secondary glioblastoma is better than or similar to the prognosis for those patients with primary glioblastoma remains controversial.

Brain tumor resection has an overall mortality rate of 1-2%.  Approximately 40% of patients have no or minimal deficits after surgery, 30% manifest no postoperative change relative to preoperative deficits, and 25% sustain an increased postoperative deficit that usually improves.

Despite extensive clinical trials, individual prediction of clinical outcome has remained an elusive goal. Glioblastomas are among the most malignant human neoplasms, with a median survival despite optimal treatment of less than 1 year. In a series of 279 patients receiving aggressive radiation and chemotherapy, only 5 of 279 patients (1.8%) survived longer than 3 years.^[42]

Patient survival depends on a variety of clinical parameters. Younger age, higher Karnofsky performance scale (a standard measure of the ability of patients with cancer to perform daily tasks) score at presentation, radiotherapy, and chemotherapy all correlate with improved outcome. Clinical evidence also suggests that a greater extent of resection favors longer survival.^{[43, 44, 45, 46]} Tumors that are deemed unresectable due to location (eg, in the brainstem) also portend a poorer prognosis.^[47]

A review by Perrini et al of 48 patients with recurrent glioblastoma found that preoperative performance status at recurrence and subtotal versus gross-total repeat resection were independent predictors of survival. These authors concluded that gross-total resection at repeat craniotomy is associated with longer overall survival and should be performed whenever possible in patients with recurrent glioblastoma who have good performance status.^[48]

Survival has not been shown to correlate with p53, EGFR, or MDM2 mutations.^[49]

Two separate reviews of outcomes in elderly patients have been published. One found that although elderly patients have a poor prognosis, gross-total resection confers a modest survival benefit and treatment with bevacizumab significantly increased overall survival. Older age and preoperative Karnofsky Performance Scale score also were significant prognostic factors.^[50]

The results of the second study concurred that there is a survival advantage for those who undergo maximal safe resection. The review also found that radiotherapy extends survival in selected patients and temozolomide chemotherapy is safe and extends the survival of patients with tumors that harbor O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation.^[51]

A study by Li et al used an updated Radiation Therapy Oncology Group (RTOG) GBM database to produce a simplified original recursive partitioning analysis (RPA) model combining classes V and VI. This resulted in 3 distinct prognostic groups defined by performance status, age, neurologic function, and extent of resection. This classification will be used in future RTOG GBM trials.^[52]

Clearly, new approaches for the management of glioblastomas are necessary. Enrollment of patients into clinical trials will generate new information regarding investigational therapies. Novel approaches, such as the use of gene therapy and immunotherapy, as well as improved methods for the delivery of antiproliferative, antiangiogenic, and noninvasive therapies, provide hope for the future.

A study by Kaur et al determined that the presence of a large cyst in patients with GBM does not affect overall survival compared with those who do not have a cyst.^[53]

• References

Patient Education

For patient education information, see the Brain Cancer Health Center. In addition, information about glioblastoma (and other brain tumors) is available from the American Brain Tumor Association (ABTA) at Brain Tumor Information.

• References

History

The clinical history of patients with glioblastoma multiformes (GBMs) usually is short, spanning less than 3 months in more than 50% of patients, unless the neoplasm developed from a lower-grade astrocytoma. Note the following:

• The most common presentation of patients with glioblastomas is a slowly progressive neurologic deficit, usually motor weakness. However, the most common symptom experienced by patients is headache.
• Alternatively, patients may present with generalized symptoms of increased intracranial pressure (ICP), including headaches, nausea and vomiting, and cognitive impairment.
• Seizures are another common presenting symptom.

• References

Physical Examination

Neurologic symptoms and signs affecting patients with glioblastomas can be either general or focal and reflect the location of the tumor. General symptoms include headaches, nausea and vomiting, personality changes, and slowing of cognitive function. Note the following:

• Headaches can vary in intensity and quality, and they frequently are more severe in the early morning or upon first awakening.
• Changes in personality, mood, mental capacity, and concentration can be early indicators or may be the only abnormalities observed.
• Focal signs include hemiparesis, sensory loss, visual loss, aphasia, and others.
• Seizures are a presenting symptom in approximately 20% of patients with supratentorial brain tumors.

• References

Laboratory Studies

Currently, no specific laboratory studies are helpful in making a diagnosis of glioblastoma.

Response to adjuvant therapy may be predicted based on the tumor's genetics.

• References

Imaging Studies

Imaging studies of the brain are essential to make the diagnosis of glioblastoma multiforme (GBM). For complete discussion, see Imaging in Glioblastoma Multiforme.

On CT scans, glioblastomas usually appear as irregularly shaped hypodense lesions with a peripheral ringlike zone of contrast enhancement and a penumbra of cerebral edema.

MRI with and without contrast is the study of choice (see the images below). These lesions typically have an enhancing ring observed on T1-weighted images and a broad surrounding zone of edema apparent on T2-weighted images. The central hypodense core represents necrosis, the contrast-enhancing ring is composed of highly dense neoplastic cells with abnormal vessels permeable to contrast agents, and the peripheral zone of nonenhancing low attenuation is vasogenic edema containing varying numbers of invasive tumor cells. Several pathological studies have clearly shown that the area of enhancement does not represent the outer tumor border because infiltrating glioma cells can be identified easily within, and occasionally beyond, a 2-cm margin.^[7]

View Image

A T1-weighted axial MRI without intravenous contrast. This image demonstrates a hemorrhagic multicentric tumor (glioblastoma multiforme [GBM]) in the ....

View Image

A T1-weighted axial MRI with intravenous contrast. Heterogenous enhancement of the lesion is present within the right temporal lobe. The hypointensity....

View Image

A T1-weighted coronal MRI with intravenous contrast. This image demonstrates the lesion (glioblastoma multiforme [GBM]) within the medial temporal lob....

View Image

A T1-weighted sagittal MRI with intravenous contrast in a patient with glioblastoma multiforme (GBM).

View Image

A T2-weighted axial MRI. The tumor (glioblastoma multiforme [GBM]) and surrounding white matter within the right temporal lobe show increased signal i....

View Image

A fluid-attenuated inversion recovery (FLAIR) axial MRI. This image is similar to the T2-weighted image and demonstrates extensive edema in a patient ....

Positron emission tomography (PET) scans and magnetic resonance (MR) spectroscopy can be helpful to identify glioblastomas in difficult cases, such as those associated with radiation necrosis or hemorrhage. On PET scans, increased regional glucose metabolism closely correlates with cellularity and reduced survival. MR spectroscopy demonstrates an increase in the choline-to-creatine peak ratio, an increased lactate peak, and decreased N- acetylaspartate (NAA) peak in areas with glioblastomas (see the image below).

View Image

Magnetic resonance (MR) spectroscopy is representative of a glioblastoma multiforme (GBM), demonstrating a high peak ratio of choline (CHO) to creatin....

A study by Piroth et al found that O-(2-[(18)F]fluoroethyl-l-tyrosine (FET) PET to measure tumor volume after surgery has a strong prognostic impact.^[8]

Cerebral angiograms are not necessary for the diagnosis or clinical management of glioblastomas.

• References

Other Tests

Electroencephalography (EEG) performed on a patient with glioblastoma multiforme may show generalized diffuse slowing and/or epileptogenic spikes over the area of the tumor. However, findings specific for glioblastoma cannot be observed on EEG.

• References

Procedures

Lumbar puncture is generally contraindicated in the setting of a brain tumor because of the possibility of transtentorial herniation with increased intracranial pressure. However, if ruling out lymphoma, it may be necessary.

CSF studies do not aid significantly in the specific diagnosis of glioblastoma multiforme.

• References

Histologic Findings

As its name suggests, the histopathology of glioblastoma multiforme is extremely variable. Glioblastoma multiformes are composed of poorly differentiated, often pleomorphic astrocytic cells with marked nuclear atypia and brisk mitotic activity. Necrosis is an essential diagnostic feature, and prominent microvascular proliferation is common. Macroscopically, glioblastomas are poorly delineated, with peripheral grayish tumor cells, central yellowish necrosis from myelin breakdown, and multiple areas of old and recent hemorrhages. Most glioblastomas of the cerebral hemispheres are clearly intraparenchymal with an epicenter in the white matter, but some extend superficially and contact the leptomeninges and dura.^{[9, 10, 11, 12, 13, 14, 15]}

Despite the short duration of symptoms, these tumors are often surprisingly large at the time of presentation, occupying much of a cerebral lobe. Undoubtedly, glial fibrillary acidic protein (GFAP) remains the most valuable marker for neoplastic astrocytes. Although immunostaining is variable and tends to decrease with progressive dedifferentiation, many cells remain immunopositive for GFAP even in the most aggressive glioblastomas. Vimentin and fibronectin expression are common but less specific.^[54]

The regional heterogeneity of glioblastomas is remarkable and makes histopathological diagnosis a serious challenge when it is based solely on stereotactic needle biopsies. Tumor heterogeneity is also likely to play a significant role in explaining the meager success of all treatment modalities, including radiation, chemotherapy, and immunotherapy.

View Image

Histopathologic slide demonstrating a glioblastoma multiforme (GBM).

• References

Staging

Completely staging most glioblastomas is neither practical nor possible because these tumors do not have clearly defined margins. Rather, they exhibit well-known tendencies to invade locally and spread along compact white matter pathways, such as the corpus callosum, internal capsule, optic radiation, anterior commissure, fornix, and subependymal regions. Such spread may create the appearance of multiple glioblastomas or multicentric gliomas on imaging studies.

Careful histological analyses have indicated that only 2-7% of glioblastomas are truly multiple independent tumors rather than distant spread from a primary site. Despite its rapid infiltrative growth, the glioblastoma tends not to invade the subarachnoid space and, consequently, rarely metastasizes via cerebrospinal fluid (CSF). Hematogenous spread to extraneural tissues is very rare in patients who have not had previous surgical intervention, and penetration of the dura, venous sinuses, and bone is exceptional.^{[16, 17, 18, 19, 20, 21]}

• References

Approach Considerations

The treatment of glioblastomas remains difficult in that no contemporary treatments are curative.^[22]  While overall mortality rates remain high, recent work leading to an understanding of the molecular mechanisms and gene mutations combined with clinical trials are leading to more promising and tailored therapeutic approaches. Multiple challenges remain, including tumor heterogeneity, tumor location in a region where it is beyond the reach of local control, and rapid, aggressive tumor relapse. Therefore, the treatment of patients with malignant gliomas still remains palliative and encompasses surgery, radiotherapy, and chemotherapy. See Brain Cancer Treatment Protocols for summarized information.

Upon initial diagnosis of glioblastoma multiforme (GBM), standard treatment consists of maximal surgical resection, radiotherapy, and concomitant and adjuvant chemotherapy with temozolomide.^{[23, 24]}  At some institutions, transferring the patient to another facility may be necessary if the proper consultations cannot be obtained. In most cases, surgical resection can be performed on an urgent, but not emergent, basis. Patients with glioblastomas who undergo surgical resection typically spend the night after surgery in an intensive care unit, followed by an inpatient stay of 3-5 days. The final length of stay depends on each patient's neurological condition.

Postoperative antibiotics usually are continued for 24 hours, and deep vein thrombosis prophylaxis is continued until patients are ambulatory. Anticonvulsants are maintained at therapeutic levels throughout the inpatient stay, while steroids are reduced gradually, tailored to each patient's clinical status. Many patients benefit from occupational therapy and physical therapy or rehabilitation.

While patients are in the hospital, they should receive postoperative imaging to determine the extent of surgical resection. Surgical resection is evaluated best within 3 days of surgery by using contrast-enhanced MRI. Contrast enhancement during this period accurately reflects residual tumor. If not performed preoperatively, complete evaluations by consulting physicians, including a neurooncologist and radiation oncologist, should be considered postoperatively.

For patients older than 70 years, less aggressive therapy is sometimes employed, using radiation or temozolomide alone.^{[25, 26, 27]}  A study by Scott et al found that elderly patients with glioblastoma who underwent radiotherapy had improved cancer-specific survival and overall survival compared with those who did not undergo radiotherapy treatment.^[28]

Evidence suggests that in patients over 60 years old, treatment with temozolomide is associated with longer survival than treatment with standard radiotherapy, and for those over 70 years old, temozolomide or hypofractionated radiotherapy is associated with prolonged survival than treatment with standard fractionated radiotherapy. The improvement in survival with temozolomide is enhanced in patients with MGMT promoter methylation.^[29]  Data from a a randomised phase 3 trial suggests that lomustine-temozolomide plus radiotherapy might be superior to temozolomide chemoradiotherapy in newly diagnosed glioblastoma with methylation of the MGMT promoter.^[55]

Stupp et al reported the final results of the randomized phase III trial for patients with glioblastoma who were treated with adjuvant temozolomide and radiation with a median follow-up of more than 5 years. Stupp et al previously reported improved median and 2-year survival when temozolomide was added to radiation therapy in glioblastoma. Survival in the combined therapy group (ie, temozolomide and radiation) continued to exceed that of radiation alone throughout the 5-year follow-up (p< 0.0001). Survival of patients who received adjuvant temozolomide with radiotherapy for glioblastoma is superior to radiotherapy alone across all clinical prognostic subgroups.^[56]   

Median time to recurrence after standard therapy is 6.9 months.^[57]  For recurrent glioblastoma multiforme, surgery is appropriate in selected patients, and various radiotherapeutic, chemotherapeutic, biologic, or experimental therapies are also employed.^{[58, 35]}

Approximately 90% of glioblastomas express cytomegalovirus (CMV) proteins, and Batich et al have reported benefit with a dendritic cell vaccine targeting CMV antigen pp65, using CMV as a proxy for glioblastoma. Patients are first treated with dose-intensified temozolomide, as the temozolomide induces lymphopenia, which provides an opportunity to retrain the immune system.

In a study of 11 patients with newly diagnosed glioblastoma received temozolomide, 100 mg/m²/d × 21 days per cycle, and at least three pp65-directed vaccines admixed with granulocyte-macrophage colony-stimulating factor on day 23 ± 1 of each cycle. Despite increased proportions of regulatory T cells (Tregs), median progression-free survival was 25.3 months and overall survival was 41.1 months; three patients remained progression-free more than 7 years after diagnosis.^[59]

Wernicke et al report that prostate-specific membrane antigen is expressed in the vasculature of GBM vessels and represents a potential novel therapeutic vascular target. Future clinical trials are planned.^[60]

• References

Medical Care

In an evidence-based clinical practice guideline formulated to address the impact of cytotoxic chemotherapy on disease control and survival in adults with progressive glioblastoma, Olson et al make the following recommendations^[61] :

• Temozolomide is recommended over procarbazine in patients who have a first relapse of glioblastoma after treatment with nitrosourea chemotherapy or who had no prior cytotoxic chemotherapy at the time of initial therapy (level II recommendation)
• Carmustine (BCNU)-impregnated biodegradable polymer wafers are recommended for use as a surgical adjunct when cytoreductive surgery is indicated; the associated toxicities must be taken into account (level II recommendation
• Various agents of uncertain benefit may be considered for use, depending on the treating clinician's clinical judgment; prior treatment exposure, systemic health, and tolerance must be taken into account; enrollment in clinical trials of these agents is encouraged (level III recommendation)

Anticonvulsant medications are usually maintained, and levels are checked intermittently. Steroids are tapered to lower doses for radiation therapy and then tapered further if possible. While taking steroids, patients should be maintained on an antiulcer agent.

Radiation therapy ^{[62, 63, 64, 65]}

Radiation therapy in addition to surgery or surgery combined with chemotherapy has been shown to prolong survival in patients with glioblastoma multiformes compared to surgery alone. The addition of radiotherapy to surgery has been shown to increase survival from 3-4 months to 7-12 months.^{[57, 66]}

Dose response relationships for glioblastomas demonstrate that a radiation dose of less than 4500 cGy results in a median survival of 13 weeks compared with a median survival of 42 weeks with a dose of 6000 cGy. This is usually administered 5 days per week in doses of 1.8-2.0 Gy.

Jablonska et al reported that in patients with poor clinical factors other than advanced age, the combination of hypofractionated radiation therapy and temozolomide produced results comparable to those seen with standard fractionation. In the 17 patients in the study, poor clinical factors included postoperative neurological complications, high tumor burden, unresectable or multifocal lesions, and potential low treatment compliance due to social factors or rapidly progressive disease. Patients received 40, 45, and 50 Gy in 15 fractions to 95% of the planning target volume (PTV), clinical target volume (CTV), and gross tumor volume (GTV), respectively. Treatment was delivered using intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT).^[67]

The responsiveness of glioblastoma multiformes to radiotherapy varies. In many instances, radiotherapy can induce a phase of remission, often marked with stability or regression of neurologic deficits as well as diminution in the size of the contrast-enhancing mass. Unfortunately, any period of response is short-lived because the tumor typically recurs within 1 year, resulting in further clinical deterioration and the appearance of an expansile region of contrast enhancement.^{[68, 69]}

Two studies investigated tumor recurrence after whole-brain radiation therapy and found that the tumor recurred within 2 cm of the original site in 90% and 78% of patients, supporting the use of focal radiation therapy. Multifocal recurrence occurred in 6% of patients in one study and in 5% of patients in a second trial.

Interstitial brachytherapy is of limited use and is rarely used. By implantation of radioactive seeds, a large dose of radiation is delivered to the tumor volume, with rapid fall-off of radiation in surrounding tissue. The tumor must be unilateral and smaller than 5 cm in diameter. In one study, patients treated with interstitial brachytherapy had a significantly better median survival (2 mo) compared with the conventional focal external beam radiation therapy. Following interstitial brachytherapy, up to 40% of patients require another surgery for removal of tissue damaged by radiation necrosis.^[70]

Experimental studies are underway in which focal radiation is delivered directly to tumors through an implanted balloon containing interstitial radiation. MRI and MR spectroscopy can be used to monitor therapy. Clinical outcomes from these studies are not yet available.

Radiosensitizers, such as newer chemotherapeutic agents,^[71] targeted molecular agents,^{[40, 41]} and antiangiogenic agents^[41] may increase the therapeutic effect of radiotherapy.^[72]

Radiotherapy for recurrent glioblastoma multiforme is controversial, though some studies have suggested a benefit to stereotactic radiosurgery or fractionated stereotactic reirradiation.^{[73, 74, 75]}  In adult patients with progressive glioblastoma, American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) guidelines recommend that when the target tumor is amenable for additional radiation, re-irradiation should be performed to improve local tumor control. This re-irradiation may take the form of conventional fractionation radiotherapy, fractionated radiosurgery, or single fraction radiosurgery.^[76]

Fleischmann et al reported that in patients undergoing re-irradiation for recurrent glioblastoma, concomitant treatment with bevacizumab significantly reduced the rate of radiation toxicity, both in the short and the long term. Bevacizumab was given in a dose of 10 mg/kg on days 1 and 15 of re-irradiation therapy.^[77]

Chemotherapy – Antineoplastic agents ^{[78, 79, 80, 81, 82, 83]}

Although the optimal chemotherapeutic regimen for glioblastoma is not defined at present, several studies have suggested that more than 25% of patients obtain a significant survival benefit from adjuvant chemotherapy. Meta-analyses have suggested that adjuvant chemotherapy results in a 6-10% increase in 1-year survival rate.^{[84, 85]}

Temozolomide is an orally active alkylating agent that is used for persons newly diagnosed with glioblastoma multiforme. It was approved by the United States Food and Drug Administration (FDA) in March 2005. Studies have shown that the drug was well tolerated and provided a survival benefit. Adjuvant and concomitant temozolomide with radiation was associated with significant improvements in median progression-free survival over radiation alone (6.9 vs 5 mo), overall survival (14.6 vs 12.1 mo), and the likelihood of being alive in 2 years (26% vs 10%).

Nitrosoureas: BCNU (carmustine)-polymer wafers (Gliadel) were approved by the FDA in 2002. Though Gliadel wafers are used by some for initial treatment, they have shown only a modest increase in median survival over placebo (13.8 vs. 11.6 months) in the largest such phase III trial, and are associated with increased rates of CSF leak and increased intracranial pressure secondary to edema and mass effect.^{[86, 87]}

MGMT is a DNA repair enzyme that contributes to temozolomide resistance. Methylation of the MGMT promoter, found in approximately 45% of glioblastoma multiformes, results in an epigenetic silencing of the gene, decreasing the tumor cell's capacity for DNA repair and increasing susceptibility to temozolomide.^[88] Note the following:

• When patients with and without MGMT promoter methylation were treated with temozolomide, the groups had median survivals of 21.7 versus 12.7 months, and 2-year survival rates of 46% versus 13.8%, respectively.
• Though temozolomide is currently a first-line agent in the treatment of glioblastoma multiforme, unfavorable MGMT methylation status could help select patients appropriate for future therapeutic investigations.^[89]
• O6-benzylguanine and other inhibitors of MGMT as well as RNA interference-mediated silencing of MGMT offer promising avenues to increase the effectiveness of temozolomide and other alkylating antineoplastics, and such agents are under active study.^{[89, 90, 37]}

Carmustine (BCNU) and cis -platinum (cisplatin) have been the primary chemotherapeutic agents used against malignant gliomas. All agents in use have no greater than a 30-40% response rate, and most fall into the range of 10-20%.

Data from the University of California at San Francisco indicate that, for the treatment of glioblastomas, surgery followed by radiation therapy leads to 1-, 3-, and 5-year survival rates of 44%, 6%, and 0%, respectively. By comparison, surgery followed by radiation and chemotherapy using nitrosourea-based regimens resulted in 1-, 3-, and 5-year survival rates of 46%, 18%, and 18%, respectively.

A major hindrance to the use of chemotherapeutic agents for brain tumors is the fact that the blood-brain barrier (BBB) effectively excludes many agents from the CNS. For this reason, novel methods of intracranial drug delivery are being developed to deliver higher concentrations of chemotherapeutic agents to the tumor cells while avoiding the adverse systemic effects of these medications.

Pressure-driven infusion of chemotherapeutic agents through an intracranial catheter, also known as convection-enhanced delivery (CED), has the advantage of delivering drugs along a pressure gradient rather than by simple diffusion. CED has shown promising results in animal models with agents including BCNU and topotecan.^{[91, 92, 93]}

Initial attempts investigated the delivery of chemotherapeutic agents via an intraarterial route rather than intravenously. Unfortunately, no survival advantage was observed.

Chemotherapy for recurrent glioblastoma multiforme provides modest, if any, benefit, and several classes of agents are used. Carmustine wafers increased 6-month survival from 36% to 56% over placebo in one randomized study of 222 patients, though there was a significant association between the treatment group and serious intracranial infections.^{[94, 95]}

Genotyping of brain tumors may have applications in stratifying patients for clinical trials of various novel therapies.

The anti-angiogenic agent bevacizumab was approved by the U.S. Food and Drug Administration for recurrent glioblastoma in May 2009.^[96] When used with irinotecan, bevacizumab improved 6-month survival in recurrent glioma patients to 46% compared with 21% in patients treated with temozolomide.^{[97, 98]} This bevacizumab and irinotecan combination for recurrent glioblastoma multiforme has been shown to improve survival over bevacizumab alone.^[99] Anti-angiogenic agents also decrease peritumoral edema, potentially reducing the necessary corticosteroid dose.

A small proportion of glioblastomas responds to gefitinib or erlotinib (tyrosine kinase inhibitors). The simultaneous presence in glioblastoma cells of mutant EGFR (EGFRviii) and PTEN was associated with responsiveness to tyrosine kinase inhibitors, whereas increased p-akt predicts a decreased effect.^{[100, 101, 102]} Other targets include PDGFR, VEGFR, mTOR, farnesyltransferase, and PI3K.

Other therapy modalities under investigation include gene therapy, peptide and dendritic cell vaccines, synthetic chlorotoxins, and radiolabeled drugs and antibodies.^{[103, 104, 105, 106, 107, 108]}

A population-based analysis of 5607 adult patients with glioblastoma in the SEER (Surveillance Epidemiology and End Results) database found that bevacizumab therapy may improve survival. In the study, glioblastoma patients who died in 2010 (after the FDA approved bevacizumab for this condition) survived significantly longer than those who died of the disease in 2008. Median survival was 8 months for patients who died in 2006, 7 months in 2008, and 9 months in 2010. This difference in survival was highly significant between 2008 (pre-bevacizumab) and 2010 (post-bevacizumab). This survival difference was unlikely due to improvements in supportive care during this time interval, because there was no significant difference between those who died in 2006 and patients who died 2 years later, in 2008.^{[109, 110]}

Electric-field therapy

The Optune device uses low-intensity, intermediate-frequency, alternating electric fields (tumor- treating fields) to target dividing cells in glioblastoma multiforme while generally not harming normal cells. The tumor-treating fields are generated via electrodes placed directly on the scalp. To target the tumor, array placement is based on the individual patient's magnetic resonance imaging results.^[111]

Optune, also known as the NovoTTF-100A System, was initially approved in 2011 for use in glioblastoma multiforme that had recurred or progressed after treatment. In October 2015, the FDA expanded approval to include use of the device in conjunction with temozolomide chemotherapy in the first-line setting. Approval was based on an open-label, randomized phase 3 trial in 700 patients, in which median overall survival was 19.4 months with use of the device plus temozolomide, versus 16.6 months with chemotherapy only.^[111]

In a randomized, open-label trial in 695 patients with glioblastoma, the addition of  tumor-treating fields to treatment with temozolomide improved median progression-free survival from 4.0 months to 6.7 months (hazard ratio [HR], 0.63; 95% confidence index [CI], 0.52-0.76; P < 0.001). Median overall survival improved from 16.0 months to 20.9 months (HR, 0.63; 95% CI, 0.53-0.76; P <  0.001).^{[112, 113]}

Modified polio vaccine therapy

The poliovirus receptor CD155 is broadly upregulated on the surface of malignant solid tumors, and a preliminary study of intratumoral infusion of a modified poliovirus vaccine has demonstrated benefit in some cases of recurrent  malignant glioma. In a dose-finding and toxicity study, 61 patients with recurrent supratentorial WHO grade IV malignant glioma received seven doses of a live attenuated poliovirus type 1 vaccine with its cognate internal ribosome entry site replaced with that of human rhinovirus type 2. The recombinant nonpathogenic polio–rhinovirus chimera was infused into the glioma via an implanted catheter.^[114]

In contrast to overall survival rates in a historical control group, which declined steadily to 14% at 24 months and 4% at 36 months, overall survival in the study patients stabilized at 21% at 24 months, remaining at that rate through 36 months. Adverse events that affected more than 20% of the study patients in the dose-expansion phase included headache (52%), hemiparesis (50%), seizure (45%), dysphasia (28%), and cognitive disturbance (25%).^[114]

• References

Surgical Care

Oral aminolevulinic acid (ALA; Gleolan) was approved by the FDA in June 2017 as an adjunct for visualization of malignant tissue during surgery in patients with malignant glioma (suspected WHO grades III or IV on preoperative imaging). During surgery, an operating microscope adapted with a blue-emitting light source and filters for excitation light of wavelength 375-440 nm, and observation at wavelengths of 620-710 nm is used to visualize PpIX (an ALA metabolite) accumulation in tumor cells that shows up as red fluorescence.^[115]

Fluorescence-guided surgery (FGS), an emerging technology that combines detection devices with fluorescent contrast agents, may provide more complete and precise resection of gliomas. Tozuleristide (BLZ-100), a near-infrared imaging agent composed of the peptide chlorotoxin and a near-infrared fluorophore indocyanine green, is a candidate for FGS of glioma and other tumor types. In a phase 1 study, tozuleristide (BLZ-100) provided a viable fluorescence signal in both high- and low-grade glial tumors, but did not bind to normal tissues. Signal intensity in high-grade tumors was found to improve with increasing doses of tozuleristide, regardless of the time of dosing relative to surgery.^{[116, 117]}

The extent of surgery (biopsy vs resection) has been shown in a number of studies to affect length of survival. In a study by Ammirati and colleagues (1987), patients with high-grade gliomas who had a gross total resection had a 2-year survival rate of 19%, while those with a subtotal resection had a 2-year survival rate of 0%.^[118]

In another study of 416 patients, gross total resection, defined as >98% on MRI, conferred a survival advantage over subtotal resection (13 vs 8.8 mo).^[46]

In another study of 92 patients, a total tumor resection without any residual disease resulted in a median survival of 93 weeks, whereas the smallest percent of resection (< 25%) and greatest volume of residual tumor (>20 cm³) gradually shortened the survival to 31 weeks and 50 weeks, respectively.^[45]

An analysis of 28 studies found a mean duration of survival advantage of total over subtotal resection for glioblastoma multiforme (14 vs 11 mo).^{[44, 119]}

Li and colleagues compared the survival of patients having 100% removal of the contrast-enhancing tumor, with or without additional resection of the surrounding FLAIR abnormality region to that of patients undergoing 78% to < 100% extent of resection of the enhancing mass. The median survival time for patients acheiving complete resection (15.2 months) was significantly longer than that for patients undergoing less than complete resection (9.8 months; p < 0.001). The patients who underwent resection of ≥ 53.21% of the surrounding FLAIR abnormality beyond the 100% resection achieved significant prolongation of survival (median survival times 20.7).^[120]

Because these tumors cannot be cured with surgery, the surgical goals are to establish a pathological diagnosis, relieve mass effect, and, if possible, achieve a gross total resection to facilitate adjuvant therapy.^[121] Most glioblastomas recur in and around the original tumor bed, but contralateral and distant recurrences are not uncommon, especially with lesions near the corpus callosum. The indications for reoperation of malignant astrocytomas after initial treatment with surgery, radiation therapy, and chemotherapy are not firmly established. Reoperation is generally considered in the face of a life-threatening recurrent mass, particularly if radionecrosis rather than recurrent tumor is suspected as the cause of clinical and radiographic deterioration. PET scans and MR spectroscopy have proven useful in discriminating between these 2 entities.

See the images below.

View Image

Axial CT scan without intravenous contrast. This image reveals a large right temporal intraaxial mass (glioblastoma multiforme [GBM]). Extensive surro....

View Image

A T1-weighted axial MRI without intravenous contrast. This image demonstrates a hemorrhagic multicentric tumor (glioblastoma multiforme [GBM]) in the ....

View Image

A T1-weighted axial MRI with intravenous contrast. Heterogenous enhancement of the lesion is present within the right temporal lobe. The hypointensity....

View Image

A T1-weighted coronal MRI with intravenous contrast. This image demonstrates the lesion (glioblastoma multiforme [GBM]) within the medial temporal lob....

View Image

A T1-weighted sagittal MRI with intravenous contrast in a patient with glioblastoma multiforme (GBM).

View Image

A T2-weighted axial MRI. The tumor (glioblastoma multiforme [GBM]) and surrounding white matter within the right temporal lobe show increased signal i....

View Image

A fluid-attenuated inversion recovery (FLAIR) axial MRI. This image is similar to the T2-weighted image and demonstrates extensive edema in a patient ....

View Image

Histopathologic slide demonstrating a glioblastoma multiforme (GBM).

Although no formal studies have been performed, observations indicate that variables, such as young age, prolonged interval between operations, and extent of the second surgical resection, have prognostic significance.^[122]

A study by El Hindy et al found that a common regulatory single-nucleotide polymorphism (-938C>A) is a survival prognosticator and a marker for high-risk in patients with glioblastoma multiforme who undergo gross total resection.^[123]

Stereotactic biopsy followed by radiation therapy may be considered in certain circumstances. These include patients with a tumor located in an eloquent area of the brain, patients whose tumors have minimal mass effect, and patients in poor medical condition, precluding general anesthesia. Median survival after stereotactic biopsy and radiation therapy is reported to be from 27-47 weeks.^[124]

A study by Jakola et al found that surgical procedures may not significantly alter the quality of life (QOL) in the average patient, however, the use of intraoperative ultrasonography may be associated with a preservation of QOL in that it helps avoid introducing new deficits.^[125]

• References

Consultations

Patients with glioblastomas should be evaluated by a team of specialists, including a neurologist, neurosurgeon, neurooncologist, and radiation oncologist, in order to develop a coordinated treatment strategy.

• References

Activity

No universal restrictions on activity are necessary for patients with glioblastomas. The patient's activity depends on his or her overall neurologic status. The presence of seizures may prevent the patient from driving. In many circumstances, physical therapy and/or rehabilitation are extremely beneficial. Activity is encouraged to reduce the risk of deep venous thrombosis.

• References

Guidelines Summary

The National Comprehensive Cancer Network (NCCN) has released guidelines on central nervous system (CNS) cancers which includes recommendations for the diagnosis and treatment of glioblastomas (grade IV gliomas). The goals of surgery are to obtain a diagnosis, alleviate symptoms of increased intracrainial pressure or compression, increase survival, and decrease the need for corticosteroids. Adjuvant treatment options depend on the patient performance status (PS), age and MGMT promoter methylation status.^[126]  

Category 1 recommendations for first-line treatment^[126] :

• Patients 70 years or younger, with good PS, regardless of the tumor's MGMT methylation status should receive fractionated standard brain RT plus concurrent and adjuvant temozolomide (TMZ) with or without alternating electric field therapy.
• Patients older than 70 years, with good PS and MGMT promoter-methylated tumors should receive hypofractionated brain RT plus concurrent and adjuvant TMZ or standard brain RT plus concurrent and adjuvant TMZ and alternating electric field therapy.
• Patients older than 70 years, with good PS and MGMT unmethylated or indeterminant tumors should receive standard brain RT plus concurrent and adjuvant TMZ and alternating electric field therapy.

• References

Medication Summary

No specific medications exist to treat glioblastomas. However, certain conditions require medical treatment. For seizures, the patient usually is started on levetiracetam (Keppra), phenytoin (Dilantin), or carbamazepine (Tegretol). Levetiracetam is often used because it lacks the effects on the P450 system seen with phenytoin and carbamazepine, which can interfere with antineoplastic therapy. Vasogenic cerebral edema is typically managed with corticosteroids (eg, dexamethasone), usually in combination with some form of antiulcer agent (eg, famotidine, ranitidine). The American Academy of Neurology's practice parameters state that prophylactic antiepileptic drugs (AEDs) should not be administered routinely to patients with newly diagnosed brain tumors (standard) and should be discontinued in the first postoperative week in patients who have not experienced a seizure.^[127]

• References

Temozolomide (Temodar)

• Dosing, Interactions, etc.

Clinical Context:  Oral alkylating agent converted to MTIC at physiologic pH; 100% bioavailable; approximately 35% crosses the blood-brain barrier. Indicated for glioblastoma multiforme combined with radiotherapy. Significant overall survival improvement was demonstrated in patients treated with temozolomide and radiation compared with radiotherapy alone.

• References

Carmustine (BiCNU)

• Dosing, Interactions, etc.

Clinical Context:  Alkylates and cross-links DNA strands, inhibiting cell proliferation.

• References

Cisplatin (Platinol)

• Dosing, Interactions, etc.

Clinical Context:  Inhibits DNA synthesis and, thus, cell proliferation by causing DNA crosslinks and denaturation of double helix.

• References

Erlotinib (Tarceva)

• Dosing, Interactions, etc.

Clinical Context:  Pharmacologically classified as a human epidermal growth factor receptor type 1/epidermal growth factor receptor (HER1/EGFR) tyrosine kinase inhibitor. EGFR is expressed on the cell surface of normal cells and cancer cells. Indicated for locally advanced or metastatic non-small cell lung cancer after failure of at least one prior chemotherapy regimen.

• References

Gefitinib (Iressa)

• Dosing, Interactions, etc.

Clinical Context:  An anilinoquinazoline. Indicated as monotherapy to treat locally advanced or metastatic non-small cell lung cancer after failure of both platinum-based and docetaxel chemotherapies. The mechanism is not fully understood. Inhibits tyrosine kinases intracellular phosphorylation associated with transmembrane cell surface receptors.

• References

Class Summary

Although the optimal chemotherapeutic regimen for glioblastoma is not yet defined, several studies have suggested significant survival benefit from adjuvant chemotherapy.

• References

Levetiracetam (Keppra)

• Dosing, Interactions, etc.

Clinical Context:  Used as adjunct therapy for partial seizures and myoclonic seizures. Also indicated for primary generalized tonic-clonic seizures. Mechanism of action is unknown.

• References

Phenytoin (Dilantin)

• Dosing, Interactions, etc.

Clinical Context:  Acts to block sodium channels and prevent repetitive firing of action potentials. As such, it is a very effective anticonvulsant. First-line agent in patients with partial and generalized tonic-clonic seizures.

• References

Carbamazepine (Tegretol)

• Dosing, Interactions, etc.

Clinical Context:  Like phenytoin, acts by interacting with sodium channels and blocking repetitive neuronal firing. First-line agent in patients with partial and tonic-clonic seizures. Serum levels should be checked and should be approximately 4-8 mcg/mL.

• References

Class Summary

These agents are used to treat and prevent seizures.

• References

Dexamethasone (Decadron)

• Dosing, Interactions, etc.

Clinical Context:  Postulated mechanisms of action in brain tumors include reduction in vascular permeability, cytotoxic effects on tumors, inhibition of tumor formation, and decreased CSF production.

• References

Class Summary

These agents reduce edema around the tumor, frequently leading to symptomatic and objective improvement.

• References