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Yr 2 - Control > Clinical - Tumours of the CNS > Flashcards

Clinical - Tumours of the CNS Flashcards

1
Q

CNS tumours require an integrated diagnosis. What 3 aspects does this include?

A
  1. Histology
  2. WHO - Grade
  3. Genetic
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2
Q

What % of lung cancers spread to the brain?

A

20%

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3
Q

What is a glioma?

A

Glioma is a type of tumor that begins in the glial (supportive) cells that surround nerve cells and help them function.

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4
Q

What is a meningioma?

A

A meningioma is a tumor that forms on membranes that cover the brain and spinal cord just inside the skull (meninges)

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5
Q

What is a blastoma?

A

A blastoma is a type of cancer caused by malignancies in precursor cells, which are commonly referred to as blasts

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6
Q

What is a medulloblastoma?

A

Medulloblastoma is the most common type of cancerous brain tumor in children - most commonly starts in the cerebellum.

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7
Q

There are 4 major types of glial cells in the CNS?

A
  1. Astrocytes
  2. Oligodendrocytes
  3. Ependymal cells and choroid plexus cells
  4. Microglia
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8
Q

Function of astrocytes?

A
  • Support and protection
  • Bridge blood to the neurones, providing nutrition
  • Also metabolise the nutrients so that they are suitable for the neurones.
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9
Q

Function of oligodendrocytes?

A

myelin production

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10
Q

Function of microglia?

A
  • As the resident macrophage cells, they act as the first and main form of active immune defense in the central nervous system (CNS).
  • Come from mesoderm
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11
Q

What are ependymal cells?

A

The cell type lining the brain ventricles. As non-neuronal cells in the brain and derived from neuroectoderm, they are clearly defined as a subtype of glial cells.

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12
Q

Function of ependymal cells and choroid plexus cells?

A

Produce CSF

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13
Q

What is the GFAP stain in histology? What is it useful for?

A
  • Done to determine whether cells contain glial fibrillary acidic protein, a protein secreted by a normal astrocyte
  • It is useful for determining whether a tumour is of glial origin
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14
Q

Histology of CNS tumours. What is the criteria?

A
  • mitosis: for cell division
  • vascular endothelial proliferation: more blood vessels to supply growing tumour
  • necrosis: tumour necrosis factor secreted by tumour to remove competition, kill the environment
  • dedifferentiation: Cell dedifferentiation is the process by which cells grow reversely from a partially or terminally differentiated stage to a less differentiated stage
    • loss of functional brain cells to promote growth
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15
Q

CNS tumours can be graded 1-4 (WHO). Describe each grade

A
  • 1: benign, no recurrence, no/very slow progression
  • 2: low grade, progression to 3 (astrocytoma 6-7year)
  • 3: high grade, rapid progression (astrocytoma 2-3years)
  • 4: aggressive
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16
Q

Molecular genetic ring:

A
  • Inner ring –> driver of mutation
    • IDH is the most common, leading to uncontrolled cell division
  • Middle ring –> additional mutations
    • With time, additional mutations in the middle ring will occur. These affect the survival of the cell e.g. EGFR
  • Outer ring –> histological diagnosis
    • Determines the prognosis
    • H3G34R with ATRX and GBM lead to poor prognosis, for example
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17
Q

What are Schwann cells?

A

Schwann cells are a type of glial cells of the peripheral nervous system that help form the myelin sheath around the nerve fibers.

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18
Q

What is a Schwannoma?

A
  • Tumour of Schwann cells
  • Benign but difficult to remove
  • Usually just grade 1
  • Mitosis is normally not seen
19
Q

Which tumours would require oncology?

A
  • High grade glioma, especially glioblastoma.
    • Without treatment, outcome after surgery is poor.
  • Low grade glioma.
    • Significant cause of morbidity and disability, often not surgically curable
  • Benign tumours (meningiomas, pituitary adenomas, schwannomas) – still affected by radiotherapy and chemotherapy due to loss of blood supply
  • Paediatric (e.g. medulloblastoma, germ cell, ependymoma)
20
Q

Presentation of brain tumours?

A
  • Pressure symptoms: headache, confusion, reduced conscious level, nausea and vomiting
  • Seizures (50%)
  • Focal symptoms due to location (e.g. weakness, dysphasia)
21
Q

Why are seizures more common in low grade tumours?

A

As some electrical activity is occurring

22
Q

When would a scan be ordered when a patient presents with potential brain tumour symptoms?

A

Scan ordered if someone presents with a headache and neurological sign/symptoms

23
Q

Where is language processed in the brain?

A

Usually located in the left (dominant) hemisphere of the brain, specifically in two areas:

  1. Broca’s area (associated with speech production and articulation)
  2. Wernicke’s area (associated with comprehension).
24
Q

A 40 year old right handed plumber presents to A & E after a fit and has a 2 week history of gradually increasing numbness and weakness of right side. Where is the lesion?

A
  • Lesion likely to be in left hemisphere of brain
  • Motor and sensory symptoms; involving both sides of central sulcus (frontal and parietal lobes –> left fronto-parietal region
25
Q

A 30 year old mother can’t make her children understand what she is trying to say. She seems to understand what is said to her. She is right-handed. Where is the lesion?

A
  • Broca’s area affected in left hemisphere (associated with speech production and articulation) –> left temporo-frontal region
  • Expressive dysphasia –> difficulty expressing what you want to say
26
Q

A 50 year old company director becomes withdrawn, apathetic and bad-tempered - then develops headaches and vomiting. Where is the lesion?

A
  • Frontal lobe; involved in higher order functioning e.g. personality, behaviour, planning, timekeeping
  • Pressure symptoms
27
Q

A 55 year old lady can’t dress herself properly, has numbness down one side and develops headaches. Which lobe of the brain is likely to be affected?

A
  • Parietal lobe; sensory loss, dyspraxia, inattention
  • Pressure symptoms
28
Q

Which lobe of the brain is involved in higher order functioning e.g. personality, behaviour, planning, timekeeping?

A

Frontal lobe

29
Q

What is radiotherapy?

A
  • Use of X-rays to treat tumours. Carefully controlled high energy X-ray beams are focused on the tumour
  • Beams travel through the skin to the tumour.
30
Q

What are xrays? How are they effective against cancer?

A
  • X-rays deliver photons, produced by naturally occurring radioactive decay
  • Cause disruption of atomic/molecular structure, including DNA
  • Affects tumour cells because they are under mitotic stress.
    • They will be ineffective at repairing damage to DNA due to X-rays.
    • Specific damage is DNA base damage, single strand breaks and double strand breaks (thought to be the most significant)
31
Q

What is external beam radiotherapy?

A
  • External beam radiotherapy is given from a radiotherapy machine outside the body.
  • High energy X-ray beams to penetrate tissue
  • Linear accelerator
  • Beams designed to target tumour and avoid normal tissue
32
Q

Typical radiotherapy regime?

A
  • Small doses built up over several weeks
  • Often 5 days on, 2 days off to allow for cellular repair of normal tissue
33
Q

What is proton radiotherapy?

A

Proton beam therapy is a type of radiotherapy that uses a beam of high energy protons rather than photons (high energy x-rays) to treat specific types cancer

34
Q

Why is proton therapy often preferred in children where whole body dose can be needed OR if near sensitive normal tissue?

A
  • A proton beam delivers some radiation to healthy tissue in reaching the tumour but very little radiation beyond the edge of the tumour being treated.
    • I.e. No dose beyond end of beam: dose goes into tumour and then stops, does not leave
  • More specific dose delivery, spares normal tissue
  • In an older person, low dose to normal brain tissue may not have a significant effect.
35
Q

What are the acute side effects of cranial radiotherapy?

A

First few weeks after RT:

  • Cerebral oedema causing raised intracranial pressure and exacerbation or pre-RT neurological symptoms, less common
  • Hair loss
  • Scalp/ear erythema
36
Q

What are the immediate side effects of cranial radiotherapy (within a few weeks/few months)?

A
  • Somnolence syndrome (severe tiredness) and exacerbation of existing neurological symptoms
  • Due to short term demyelination of neurones
  • Self-limiting
37
Q

What is somnolence syndrome?

A
  • Somnolence syndrome is a collection of symptoms consisting of drowsiness, lethargy and fatigue (hypersomnia)
  • It is linked to receiving radiation therapy to the head.
  • The symptoms of somnolence syndrome usually happen 3 to 12 weeks after radiation therapy ends.
38
Q

What are the late effects (several months to years after RT)?

A

Damage to sensitive structures e.g. lens (cataracts), pituitary (hypopituitarism), cerebral hemispheres (memory loss)

Shield these from the radiation as much as possible.

39
Q

For a high grade glioma (3/4), when would radiotherapy not be carried out?

A

If elderly or poor PS, patient may die of brain tumour within 3 months before recovering from side-effects, therefore not recommended

40
Q

For a high grade glioma (3/4), when would radiotherapy be carried out?

A

If young and fit and can live for several years, RT recommended

41
Q

Median survival of grade 1-4 gliomas?

A
  • Grade 1: many years (cured if complete resection)
  • Grade 2: 5-12 years
  • Grade 3: 2-4 years
  • Grade 4: 6-18 months (depending on prognostic factors)
42
Q

What are 5 common cancers that can cause brain metastases?

A

breast, bowel, lung, prostate, kidney

43
Q

What is gamma knife treatment?

A

highly targeted radiation after pinning the patient into place

44
Q
A

Yr 2 - Control (71 decks)

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