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Medulloblastoma > Background and recommendations > Flashcards

Background and recommendations Flashcards

1
Q

High risk CSI dose

A

36 Gy at 1.8 Gy per fraction

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2
Q

Standard risk CSI dose

A

23.4 Gy at 1.8 Gy per fraction

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3
Q

What factors make a patient Standard Risk?

A
  1. Age > 3 year
  2. GTR/STR with < 1.5 cm2 residual
  3. M0
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4
Q

What factors make a patient High risk?

A
  1. Anaplastic or large cell histology
  2. < 3 years old
  3. > 1.5 cm2 residual tumor
  4. M+
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5
Q

What is the most common location of medulloblastomas?

A

The cerebellar vermis where the tumor grows and usually fills the 4th ventricle

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6
Q

What are the WHO subtypes of medulloblastoma?

A
  1. Classic
  2. Nodular/Desmoplastic
  3. Anaplastic/Large cell
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7
Q

What is the unfavorable histology of medulloblastoma?

A
  1. Anaplastic/Large cell
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8
Q

What are the only plan considerations in terms of the brain or spinal cord?

A

Hot spots or colds spots over the brain or cord should be minimized?

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9
Q

What is the median age of disease?

A

Bimodal age distribution:

7 years old

25 years old

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10
Q

What percentage of patients have CSF spread at diagnosis?

A

30-40%

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11
Q

When it spreads outside of the CNS, where does it go?

A

Bone

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12
Q

What clinical features make desmoplastic/nodule subtype unique?

A
  1. LOH 9q
  2. Older age at diagnosis
  3. Better prognosis
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13
Q

What percentage of MBs are familial? What syndromes are associated with it?

A

5%
Gorlin (PTCH)
Turcot (APC) mutation

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14
Q

What is the DDx of posterior fossa mass?

A 
MB
AT/RT
Ependymoma 
Astrocytoma 
Brainstem glioma
JPA
Hemangioblastoma 
Metastasis
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15
Q

What elements of the history and physical do you want to know about?

A

Sx: headaches, nausea, vomiting, confusion, focal neurologic deficit, difficulty walking

PE: CN exam looking for diplopia (CN VI), head bob, truncal ataxia, downward deviation of gaze, fundoscopic exam

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16
Q

What is the sun setting sign?

A

Downward deviation of gaze from increased ICP leading the deficits of CN III, IV and VI

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17
Q

What imaging is needed?

A

MRI of the spine and brain
CXR
Consider Bone scan

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18
Q

How is a tissue diagnosis acquired?

A

Tumor resection

BM Bx

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19
Q

What labs are needed?

A

CBC/CMP and pregnancy test

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20
Q

What ancillary tests should be performed?

A

Baseline audiometry, IQ testing, TSH, and growth and development measurements

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21
Q

What post op studies are done?

A

LP 10-14 days post op

MRI brain 24-48 hours post-op

22
Q

What is the first step of treatment?

A

Ventricular shunt/drain
Steroids
Diamox

23
Q

T stages (Chang): T1 or T2

A

T1: 3 cm or less and localized
T2: > 3 cm

24
Q

How are NTR, STR and Bx only defined?

A

NTR: <50% resection

25
Q

T stages (Chang): T3 or T4

A

T3a: Tumor extends to the aqueduc of sylvius or foramen of Luscka

T3b: Tumor extends to brain stem

T4: Extends beyond aqueduct of sylvius or foramen magnum

26
Q

M stage (modified Chang)

A 
M0: no mets 
M1: +CSF 
M2: nodular seeding intracranially 
M3: nodule in subarachnoid space in the cord 
M4: extraneural spread
27
Q

What is the most important prognostic factor?

A

M stage

28
Q

What is the treatment paradigm for patients with standard risk MB?

A
  1. Max safe resection
  2. RT with concurrent vincristine
  3. Adjuvant chemotherapy for 8, 6 week cycles of vincristine/CCNU/cisplatin
29
Q

What is the RT dose schedule for SR MB?

A

CSI: 23.4 Gy at 1.8 Gy/fx

Boost gross disease and resection cavity to 54 Gy

30
Q

What is the most important endocrine deficiency after RT?

A

GH deficiency and the threshold is 10 Gy

31
Q

What are the long term toxicities associated with RT?

A
  1. Ototoxicity
  2. Hypopituitarism including GH deficiency
  3. Decrease in IQ
  4. Second cancer
32
Q

What are the complications of surgery?

A
  1. PF syndrome
  2. Aseptic meningitis
  3. CSF leakage
33
Q

What is posterior fossa syndrome?

A

A syndrome that presents 12-24 hours after surgery and causing mutism, dysphagia, ataxia, hypotonia and mood lability. It usually improves over several months. It happens in 10-15% of patients.

34
Q

What is the expected 5 year DFS for SR and HR patients?

A

5 year EFS: 80% of SR and 50-60% of HR

35
Q

What factors predict greater decline of IQ after CSI?

A

Age < 7
Female gender
CSI Dose of 36 Gy
Higher IQ at baseline

36
Q

What is the treatment paradigm for children < 3?

A
  1. Max safe resection
  2. Chemotherapy until age 3
  3. CSI and local boost with vincrisitine at age 3
  4. If desmoplastic and disease free, no RT
37
Q

What is the treatment for patients with HR MB, > 3?

A
  1. Maximum safe resection
  2. RT with CSI to 36 Gy and boost PF to 54. Boost intracranial seeding to 50.4 Gy. Boost spinal mets above cord teminus to 45 Gy. Boost spinal mets below cord terminus to 50.4 Gy, Boost diffuse spinal disease to 39.6 Gy.
38
Q

Describe simulation of CSI?

A
  1. Prone
  2. Body mold
  3. Arms down
  4. Neck extended
  5. Anesthesia if needed
39
Q

Cochlea constraint?

A

V30<50%

Max dose 35 Gy with chemo

40
Q

Collins law?

A

Follow pediatric patients after RT for (age at dx + 9 months) years

41
Q

Describe the 2nd spinal field

A

use this if the length of the spinal area needed to be treated exceeds 36-38 cm
Place the inferior fields; isocenter at the junction and use a half beam block to minimize the cold spot between the two fields.
Match the fields at L-2 because this is where the depth of the cord changes the most

inferior border: 1 cm past

42
Q

Describe the cranial field set up?

A

Rotate the collimator to match the divergence of the spinal field. Rotate it arctan (1/2 length of sup spine field/SSD)

43
Q

How much do you kick the couch?

A

arctan (1/2 length of cranial field/SAD) and you kick it toward the side treated to match cranial field divergence

44
Q

When multiple spine fields are used what is the calculation for the skin gap? At what depth is the match?

A

skin gap=([0.5 x length 1 x d]/SSD1)+(0.5 x length 2 x d]/SSD2)

45
Q

What chemotherapy do you give young children to delay RT?

A
  1. Cytoxan + Vincristine x 2 then cisplatin and etopsoide x 1

If child is < 2, 24 months of chemo

If child is 2, 12 months of chemo

46
Q

Field borders of the spinal field?

A

Superior: C5-6
Inferior: below thecal sac defined on MRI but usually between S2-3
Lateral: 1 cm lateral to pedicles and 2 cm lateral to neural foramen in the sacrum

47
Q

What is the dose of concurrent vincristine?

A

1.5 mg/m2 IV weekly (max 2)

48
Q

Field borders of the cranial field?

A 
Superior: flash 
Inferior: 
0.5 cm on cribriform plate 
1 cm on the middle cranial fossa 
1 cm anterior to vertebral bodies
49
Q

For limited boost, how do you design the target volumes?

A

GTV: Residual enhancing tumor mass and the wall of the resection cavity
CTV= GTV+ 1.5 cm edited for bone and tentorial surface
PTV= CTV + 0.5 cm

50
Q

How much and how often do you use the match line between cranial and spinal field?

A

Move 1 cm superiorly every 9 Gy

Medulloblastoma (1 decks)

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