Adult CNS Tumors Flashcards
How common are brain tumors?
Brain tumors are relatively less common compared to other cancers. However, brain metastases are expected to continue to increase in incidence as cancer patients are living longer, and it is estimated that 35% of cancer patients will ultimately develop brain metastases. There are approximately 13 million cancer survivors in USA.
Development of mature neurons and their supportive glial cells from pluripotent stem cells is a highly complex process controlled by cell growth promoting and suppressing genes
Overview of Neuropoiesis
Neural Stem cells give rise to Glial progenitor and neuronal progenitor cells
Glial progenitor cells form astrocytes, ependyma, and oligodedrocytes
Neuronal progenitor cells forms neurons
There is growing evidence supporting the presence of tumor stem cells in different cancers, including glial tumors.
Glial tumors are histologically differentiated into different types and may have different clinical behavior.
Mixed glial and neuronal tumors are also possible containing neoplastic neuronal and glial component (ganglioglioma). Mixed glial tumors are also possible e.g. oligo-astrocytoma
Tumors can arise from any structure present intracranially. Give some examples.
hemangioblastoma from blood vessels,
neurofibroma and schwannoma from nerves,
lymphoma from trafficking white blood cells,
germinoma from nests of germ cells,
meningioma from arachnoid cap cells,
chordoma and chondrosarcoma from bone, or an extracranial cancer may enter brain via blood stream (metastases).
Developmental cysts may mimic a brain tumor
What are the astrocytic/glial derived brain tumors?
Glioma
Ependymoma
Oligodendroglioma
What are the nerve brain tumors?
Schwannoma
Neurofibroma
What cancers commonly MET to the brain?
Breast cancer
lung
Melanoma
Renal cell carcinoma
GI cancers
Other CNS tumors
The frequency of the various primary CNS tumors ranges from 2% for meningioma and mixed oligoastrocytoma to 40% for glioblastoma multiforme (GBM) and 42% for infiltrative astrocytoma.
What are the primary cranial intraaxial tumors?
glioma
pituitary
lymphoma
What are the primary cranial extraaxial tumors?
meningioma
acoustic neuroma
What are the risk factors for CNS tumors?
Only ionizing radiation, chemotherapy/immunosuppression and certain genetic syndromes are definitely related to development of brain tumors.
What things might cause CNS tumors?
Electromagnetic Fields, including cell phone use
Diet
Occupation
Infections (HIV, EBV, HTLV)-Epstein Barr virus is linked to CNS lymphoma in immunosuppressed patients, especially after bone marrow transplant and in patients with AIDS. This represent only a small minority of brain tumors diagnosed each year
Describe Li-Fraumeni syndrome
AD syndrome with mutation of TP53 on chromosome 17p13 causing glioma and medulloblastoma
Describe Tuberous sclerosis in relation to the brain
AD syndrome caused by TSC1/2 mutation on 9q34 and 16p13 respectively resulting in subependymal giant cell astrocytomas, cortical tubers, and glioma in the brain
Describe Neurofibromatosis type I (von Recklinghausen’s disease; NF1) in relation to the brain
AD syndrome caused by mutation of NF1 on chromosome 17q11 causing glioma (optic nerve), astrocytoma, and glioblastoma
Describe Neurofibromatosis type 2 in relation to the brain
AD syndrome caused by mutation of NF2 on chromosome 22q12 causing meningioma, schwannoma (bilateral acoustic neuroma), and ependymomas
Describe MEN1 in relation to the brain
AD syndrome caused by Menin mutation on 11q13 causing pituitary tumors
What causes Retinoblastoma?
AD syndrome caused by mutation of RB1 on chromosome 13q14
Describe VHL disease in relation to the brain
AD syndrome caused by mutation of VHL on chromosome 3p25-20 causing hemangioblastoma
What must happen for a tumor to develop?
For a tumor to develop, either cell growth genes have to be over activated, or inhibitor genes have to be silenced. Many such events have now been recognized and newer targeted therapies are being developed to counter these events
What is Cerebral perfusion pressure?
The difference between mean arterial pressure and intracranial pressure (CSF and interstitial pressure).
Describe the pressure volume curve of the brain
As the intracranial volume slowly increases (graph on the left), such as with tumor growth, intracranial pressure remains fairly constant until brain compliance threshold is reached. At that stage small volume increase causes large increase in intracranial pressure.
At this stage intermittent increase in intracranial pressure (graph on the right) may exceed cerebral perfusion pressure (plateau waves) and cause multiple symptoms from focal weakness, numbness, mental status change to seizure like activity. This is called plateau wave phenomenon and is an important concept to remember.
What are the general signs/symptoms of CNS tumors?
HA due to raised intracrnaila pressure or local irritation; often non-specific but may have migraine features; may show laterality
Vomiting
Mental status changes (depression, irritability, aparthy)
When shoudl you suspect a tumor as the source of a HA
worse on awakening with improvement within 1 hour
new onset at any age
change in character or severity of headaches in a chronic headache patient
Describe the vomiting associated with CNS tumors
may or may not be associated with nausea
occurs more often on awakening
more common in children
suggests tumor if vomiting immediately follows an acute onset headache suggesting increased ICP
Signs and symptoms of brain tumors result from what?
increased intracranial volume. This may stretch basal blood vessels or dura causing pain. Increased intracranial pressure may reduce cerebral perfusion (mean arterial pressure –intracranial pressure = perfusion pressure) and result in ischemic symptoms. Finally involvement of eloquent brain structures may produce deficits
What are some other signs of CN tumors (possible)?
- papilledemia (often asymptomatic but may cause visual changes; more common in children)
- Seizures (partial or generalized; Episodic alterations in smell, taste, personality, memory, motor or sensory function depending on the origin of neural discharge)
Focal neurologic deficits
What Focal neurologic deficits may be seen with CNS tumors?
Will vary depending on location
Includes but not limited to:
weakness (i.e. pre-central gyrus)
paresthesias (i.e.. post-central gyrus)
visual impairment (i.e.. optic pathway/occipital lobe)
personality changes (i.e.. frontal lobe)
May or may not be reversible depending on the cause (tumor invasion vs. edema vs. compression) and time since onset of deficit
Focal signs with CNS tumors result from direct involvement of eloquent brain structures. What is the pathogenesis of the seizures?
unclear and may arise from entrapped neurons in the tumor, or pressure from infiltrating tumor edge
What are common common etiologies of the signs and symptoms of CNS tumors?
Invasion of neural or vascular structures
Compression of adjacent neural or vascular structures
Obstruction of CSF pathways <–> Hydrocephalus <-> Inc ICP
Herniation from mass effect
Cerebral hypoperfusion because of increased intracranial pressure
Describe what is occurring in #1 below
1 – Subfalcine herniation of cingulate gyrus. May compress anterior cerebral artery and CVA.
Describe what is occurring in #2 below
2 – Diencephalic downward herniation. Compression of upper brainstem causes drowsiness, impaired vertical gaze and uni- or bilateral small pupils because of involvement of sympathetic fibers (Horner syndrome).
Describe what is occurring in #3 below
3- Classical uncal herniation. Causes ipsilateral oculomotor nerve palsy and contra or ipsilateral hemiparesis
Describe what is occurring in #4 and #5 below
- Upward herniation through tentorium. May cause ipsilateral oculomotor, Horner (mid position unreactive pupil) and contralateral hemiparesis.
5, Tonsillar herniation causing BP changes, weakness, respiratory disturbance, weakness and Horner syndrome.
What are some diagnostic tools for diagnosing CNS tumors
Definitive diagnosis of a CNS tumor can only be achieved through what?
tissue biopsy,
One exception is primary CNS lymphoma (PCNSL)…malignant cells may be found in the CSF via lumbar puncture
Describe T1 weighted MRI scan
–Water (i.e.. CSF, tumor, edema) is hypointense (dark): decreased signal or darker than surrounding brain
–Injected contrast that leaks across disrupted BBB within tumors appears hyperintense (bright): increased signal or brighter than surrounding brain
Describe T2 weighted MRI scan
–CSF/edema/tumor appears hyperintense (bright)
–Differentiating edema from infiltrating tumor on T2: Edema spares the cortex but Tumor does
There is a large ring enhancing tumor in the left frontal lobe. There is a mass effect with midline shift. Tumor has grown rapidly outstripping its blood supply resulting in central necrosis (darker area). All these are indicative of a highly malignant tumor, most likely a grade IV astrocytoma (GBM)
Left T2 images also show edema in the brain tissue. On T2 images stationary and moving water both appear bright or white
What is the most common brain tumor in adults?
Gliomas
Describe Gliomas and their main subtypes
Glioma is an umbrella term used to describe tumors that are derived from the supporting glial cells of the CNS. The main subtypes include:
–Astrocytoma
–Oligodendroglioma
–Ependymoma
How are gliomas graded?
With each tumor type there is a range from low to high based on behavior, imaging, and histopathological characteristics
–Juvenile Pilocystic Astrocytoma (Grade 1)
–Low-grade astrocytoma (Grade 2)
–Anaplastic astrocytoma (Grade 3)
–Glioblastoma multiforme (Grade 4, most common of all glioma types)
There is a higher probability of malignant tumors with advancing age. Tumors which start as Grade II may degenerate to higher grade after many years
Note about gliomas
Low grade tumors - more commonly seen in the younger population
High grade tumors- more commonly seen in those older than 50 years
Describe Grade I gliomas
Least malignant, grow slowly, usually non infiltrative, almost normal histological appearance, surgery alone usually effective, typically non-enhancing on T1 contrast (JPA, PXA, SEGA).
Good probability of cure with complete surgical resection
Describe Grade II gliomas
Relatively slow growing, more abnormal histological appearance, can invade (infiltrate) adjacent normal tissue, may recur, sometimes recur as a higher grade, typically non-enhancing on T1 with contrast (Low-grade Glioma). Low probability of cure even with good surgical resection. Survival over many years
Describe Grade III Gliomas
Malignant, actively reproducing abnormal cells, infiltrate adjacent normal brain tissue, tend to recur, often as a higher grade, typically enhancing on T1 contrast (Anaplastic Astrocytoma). Very low probability of cure. Median survival 2-3 years
Describe Grade IV Gliomas
Reproduce rapidly, bizarre histological appearance, infiltrate widely, induce the formation of new blood vessels so they can maintain their rapid growth, necrosis in their center (Glioblastoma Multiforme). Median survival= months
More on Gliomas
Lowest grade tumors are well differentiated, show no nuclear atypia, and have low mitotic index. Increasing de-differentiation, higher mitotic index, vascular proliferation and necrosis determine higher tumor grade. Tumor blood vessels have immature blood brain barrier resulting in leakage of dye on MRI imaging
Low grade gliomas are infiltrative, slow growing, do not produce severe mass effect, are hyper-intense on T2 or FLAIR images (left image upper row) and do not enhance with contrast (right image upper row T1 after contrast). Note features of a highly malignant glioma in the bottom row: an enhancing margin, necrotic center, surrounding edema, mass effect
How are CNS tumors managed?
Tumors are managed by symptomatic and more specific treatment.
Corticosteroids cause rapid but temporary improvement in symptoms by reducing swelling and restoring blood brain barrier.
Seizures are managed with NON ENZYME INDUCING anti seizure drugs e.g. levetiracetam, lacosamide, gabapentin etc.
T or F. Although there is a 50% lifetime risk of seizure in a brain tumor patient (primary tumor or metastasis), there is NO ROLE for starting treatment unless a seizure has occurred.
T.
How are steroids useful with CNS tumors?
Reduces vasogenic edema and improves intracranial pressure
Dramatic but temporary improvement in neurologic symptoms
Other management options for brain tumors- Observation can be an appropriate strategy in low grade tumors. Survival is improved by extent of resection and is further improved if a radiation or chemotherapy is used in combination or separately. Radiation treatment can be associated with long-term risk of cognitive decline, stroke and secondary cancers.
What are the main radiation modalities?
- Conventional (not used anymore)
- Conformal
- Radiosurgery
- Brachytherapy
- Proton therapy
Describe conformal radiation therapy work?
In conformal therapy different beams of radiation are computer graphically designed to focus on a tumor. Thus the tumor gets maximum dose while normal brain dose is reduced.
What is radiosurgery? Brachytherapy?
Radiosurgery is high dose of conformal radiation given in single fraction while brachytherapy is insertion of radioactive material in tumor cavity.
Describe proton therapy
Proton therapy is a newer technology. Protons are heavier particles and depth of radiation can be controlled, thus further sparing normal tissue. It is rapidly gaining acceptance and likely will replace photon therapy in future. Cost is prohibitive at this time.
Examples of conventional radiation. Normal tissue and tumor receive the same dose.
What are some chemo options for CNS tumors?
Conventional regimens include:
single-agent IV bis-chloroethyl-nitrosourea (BCNU; carmustine)
single-agent oral Temozolomide (current treatment of choice)
combination (PCV) of procarbazine, chloroethyl-cyclohexyl nitrosourea
(CCNU; lomustine), and vincristine
What is the standard of care for malignant glioma and is given concurrently with radiation and continued after radiation.
Single agent temozolomide. It adds approximately 3-months to median survival.
What is Temozolomide?
It is an alkylating agent and may cause serious bone marrow suppression.
Tumor DNA damaged by alkylating agent is repaired by what?
an enzyme called MGMT.
In patients with inactive MGMT, median survival is close to 2-years while there is no improvement over radiation treatment in patients with active MGMT.
What are some targeted therapies for gliomas?
Targeted therapies are being developed and many agents are under study. Bevacizumab, an antibody to vascular endothelial growth factor, is FDA approved for use at recurrence. This drug prevents new blood vessel formation and stops tumor growth.
What are the prognostic factors for gliomas?
•Survival is better if:
–Younger age
–Good performance status
–Tumor grade and histology low
–Degree of tumor resection high
–O(6)-methyl guanine-DNA methyltransferase (MGMT) methylation
–Isocitrate dehydrogenase 1 (IDH1) mutation present
–1p and 19q deletion in oligodendroglioma
Describe meningiomas
These represent 2-10% of all primary brain tumors (2nd most common primary CNS tumor behind gliomas) with a peak incidence at 45 years (women more common)
These are slow growing BENIGN tumors
Where are meningiomas derived from?
arachnoid membrane (arachnoid cap cells)
What are the subtypes of meningiomas
low grade (most common)
atypical
malignant
Where are common places to find meningiomas in the brain?
convexity, parasaggital, optic sheath
Meningiomas are extra-axial (outside brain) tumors characterized on MRI by diffuse enhancement and a dural tail. May spontaneously involute and calcify. May cause symptoms by compression of brain structures. What is their prognosis?
Low grade meningioma carry a good prognosis with surgical resection. Higher grade tumors require radiation treatment in addition to surgery.
There is no known effective chemotherapy at this time. Note spindle shaped cells arranged in sheets and whorls, and tail of enhancement over the dura extending from the tumor edge
Meningiomas
What is this?
Meningiomas - extra-axial tumors characterized by diffuse enhancement and a dural tail. May spontaneously involute and calcify. May cause symptoms by compression of brain structures.
Note spindle shaped cells arranged in sheets and whorls, and tail of enhancement over the dura extending from the tumor edge
Describe pituitary tumors
These tumors, most commonly derived from the anterior pituitary represent 10-15% of all primary brain tumors (3rd most common primary CNS tumor)
What are the main classifications of pituitary tumors?
Microadenomas (< 1cm): most often hormone secreting (AKA functional)
Macroadenomas (> 1cm): most often do not secrete hormones (AKA nonfunctional), Often grow large enough to cause compression and hypofunction of pituitary gland or compression of the pituitary stalk
Pituitary tumors are not uncommon and present with compression of surrounding structures (optic chiasm), or hormone over secretion, or deficiency.
Prolactinomas and to some extent growth hormone secreting tumors can be treated medically with dopamine agonists. Other tumors may need surgical resection with or without radiation. Bitemporal hemianopia starts with upper quadrants compared to craniopharyngioma which may start with inferior quadrants.
What are some possible signs/symptoms of pituitary tumors?
Headache
Endocrine dysfunction (galactorrhea - XS prolactin, acromegaly - XS GH)
Visual field defects- Classically bitemporal hemianopsia starting with upper quadrant (compression of chiasm)
Unilateral blindness (optic n. compression)
Diplopia (invasion of cavernous sinus compressing CN III, IV, VI)
Facial numbness (invasion of cavernous sinus compressing CN V)
How are pituitary tumors diagnosed?
MRI with and without contrast: Serum hormone levels (Endocrinology), Visual Fields Testing (Ophthalmology)
How are pituitary tumors tx?
Observation
Surgery: 1st line of treatment for most tumors; Low morbidity and mortality with experienced neurosurgeon
Radiotherapy: Adjunct for invasive tumors or subtotal resection; Reserved for recurrent or unresponsive tumors, or very small tumors that are not directly adjacent to vital structures such as optic nerve
Late complications: damage to optic nerves, hypopituitarism, hypothalamic dysfunction, secondary malignancy
What are some Pharmacotherapy options for a pituitary tumor?
Bromocriptine and Pergolide: dopamine agonists for prolactinomas, Often show a significant reduction in tumor size up to 80%
Octreotide: a somatostatin analogue, for GH secreting tumors.
Replacement therapy for pituitary hypofunction
Pituitary tumors are not uncommon and present with compression of surrounding structures (optic chiasm), or hormone over secretion and deficiency. Prolactinomas and to some extent growth hormone secreting tumors can be treated medically with dopamine agonists. Other tumors may need surgical resection with or without radiation
Describe acoustic neuromas (aka vestibular schwannoma)?
Tumor originating in schwann cells surrounding the vestibular portion of CN VIII (most commonly arise within the internal auditory canal or cerebellopontine angle)
occur in middle aged adults M=F
How do acoustic neuromas present?
Symptoms may involve hearing loss, timmutus, HA ataxia, trigeminal neuropathy, or neuralgia.
How are acoustic neuromas tx?
Small tumors may be observed.
Surgical resection may be possible (good outcome)
Radiation surgery is application of multiple radiation beams focusing on a tumor mass and may be used
Bilateral acoustic neuromas are pathognomonic for what?
NF2
Acoustic Schwannoma
Note densely packed and cystic areas in tumor _ Antoni A and B areas
Describe primary CNS lymphomas
PCNSL incidence is on the rise. It develops due to malignant transformation of trafficking B-lymphocytes and commonly affects the leptomeninges and deeper periventricular brain parenchyma
How are primary CNS lymphomas diagnosed?
MRI w/ contrast may show multiple uniformly enhancing masses with little or no edema
LP may show monoclonal population of B-cells in the CSF
Vitrectomy for tissue diagnosis if ocular involvement
How are primary CNS lymphomas tx?
Steroids: if lymphoma is suspected, withhold steroids until time of biopsy. Steroids will cause rapid necrosis and poor specimen for pathology
Chemotherapy: High-dose methotrexate, vincristine, and procarbazine
Radiotherapy
What is the prognosis for primary CNS lymphomas
Months for steroids alone; 1 year for treatment with radiation
3-4 years following treatment with chemotherapy and radiation. Cure possible in younger patients
Lymphoma is a highly chemo and radiosensitive tumor. Extent of resection is not a prognostic marker and only biopsy is performed.
Steroids are oncolytic for this tumor and should be avoided before biopsy. Blood brain barrier prevents most chemotherapy agents to enter the brain. Methotrexate crosses blood brain barrier and high doses are used to treat the tumors. Complete responses are frequently seen.
CNS lymphoma- Note round blue cells, It may be caused by EBV infection in immune compromised patients.
Are brain METs common?
More common and equally as devastating as high-grade glioma
Estimated 170,000 per year (most common CNS tumor!)
What are some common tumors that MET to the brain?
Small/Non-small cell lung cancer (50%): Most common brain metastases in males
Breast cancer (15-20%): Most common brain metastases in females
Melanoma (10%, highest propensity to met to brain)
Colon Cancer (5%)
Renal Cell Carcinoma
Unknown primary in up to 10% of Brain Metastases
How are brain METs diagnosed?
Primary workup if indicated (head to toe imaging plus serum Ca markers)
MRI with Contrast
Discrete single/multiple enhancing nodules
Significant amount of edema out of proportion to the size of the nodules
Brain metastases are now the most common brain neoplasm. Treatment depends upon status of extracranial disease. In controlled extracranial disease, surgery with or without radiation surgery prolongs survival and improves quality of life. Radiation surgery alone may be used if poor surgical risk. Whole brain radiation treatment is the treatment of choice if progressive extracranial disease
brain METs- Note multiple solid and ring enhancing lesions
What are the goals of tx brain METs?
Goals are to prolong life without incurring further neurologic deficit
What considerations must be accounted for when selecting tx for brain METs?
Considerations: number, site, size and histologic type of the lesion; the age, neurologic status, status on non-CNS disease, and overall condition of the patient
What are some tx options for brain METs?
Accessible lesions and stable extracranial disease: surgery plus whole brain radiotherapy (WBRT)
Surgically inaccessible lesions: radiosurgery or WBRT
Progressive extracranial disease or multiple metastases then WBRT only
Chemotherapy and hormonal therapy for specific histologies
What is the prognosis for brain METs?
Untreated- roughly 4-weeks
Steroids only- roughly 8 weeks
Other treatment modalities may prolong survival for up to 12 months
What should be on the Ddx for ring enhancing brain lesions?
METs
abscess
CVA
high grade glioma
lymphoma
demyelination- (An incomplete or open ring enhancement is commonly seen with a demyelinating lesion (tumefactive demyelination).
Principals of treatment of spinal cord tumor are similar to intracranial tumors. Surgical resection is technically more challenging and chemotherapy is less well studied
