Central nervous system

Question 1

glioma radiation dose grade II

Answer 1

grade II: ctv 54= gtv +15mm
45 gray 1.8 gray per fraction
9gray 1.8 gray per fraction

Question 2

glioma high grade, grade 4 dose

Answer 2

ctv 50= 50 gray 25 fraction 5 week| ctv 60=10 gray 5 fraciton 1 week

Question 3

CSI standard risk dose medulloblastoma

Answer 3

Standard risk: medulloblastoma
(classic, desmoplastic, MBEN , chang stage M0), </1.5cm of residual microscopic disease, no MYC or MYCN gene amplification)
phase 1
23.4 gy 1.8gy/fx 13 fraction in two and half wk
phase II
30.6 gray in 17 fraction total for 54 gray with ccrt vincristine 1.8 gray/fx

Question 4

csi:high risk medulloblastoma dose

Answer 4

Criteria: (medulloblastoma: large cell or anaplastic histology, Chang stage M1-3{metastases in CSF, intracranially or in the sub arachnoid space}, >1.5cm2 or residual disease, MYC or MYCN gene amplification.
Phase 1:
M0/M1: 36 gy in 20 fraction given in four weeks
M2-3: 39.6 gy in 22 fractions given in four and a half weeks
Phase 2: tumor bed boost:
Total dose of 54-55.8 gy in 30-31 fractions given in six weeks

Question 5

ependymoma radiation dose

Answer 5

54gy/30 fraction 1.8gy 6wks

Question 6

cns lymphoma rt dose

Answer 6

whole brain 40gy 20 fracitonor 45 gy 25 daily fraction wtih chemotherapy MTXcombined with rituximab or ritu+tmz

Question 7

medulloblastoma type

Answer 7

Medulloblastoma, molecularly defined
medulloblastoma, WNT activated
medulloblastoma, SHH activated and TP53 -wildtype
medulloblastoma, SHH activated and TP53 mutant
medulloblastoma, non WNT/non SHH

Question 8

medulloblastoma histological type

Answer 8

WHO classification medulloblastoma 2021
a. Medulloblastoma histologically defined (classic, desmoplastic, extensive nodularity, large
cell/anaplastic, NOS; are now in 1 section)

Question 9

Risk factor for cns tumor

Answer 9

history of radiation exposure
HIV,EBVNF1, P53, MEN1, NF2chemical: rubber compound, polyvinyl chloride, polycyclic hydrocarbon

Question 10

CSI complication

Answer 10

acute
* GIT toxicity,
* dysphagia,
* odynophagia,
* weight loss,
* myelosuppression
late
* memory deficit
* hearing problem
* growth problem

Question 11

High propensity for csf spred

Answer 11

Medulloblastoma
Pnet
Cns lymphoma

Question 12

Prognostic factors

Answer 12

Prognostic Factors
Adverse Prognostic factor
1. Pathologic grade
2. Patient age
3. Overall clinical condition/Comorbidity
Better prognosis
1.IDH1 mutation
2. LOH in chromosome
3. IP & 19q in anaplasticoligodendroglioma

Question 13

High risk factors for glioma

Answer 13

Idh mutation1p/19q deletionsAge>40yrsSize >6cmFocal neurological deficit

Question 14

Common adult primary CNS tumor

Answer 14

meningiomas 30-35%
GBM 20%
pituitarynerve sheath tumor 10%
low grade glioma 5%
anaplastic astrocytoma <5%
primary cns lymphoma <5%

Question 15

Common children CNS tumor

Answer 15

pilocytic astrocytoma 20%
malignant glioma/GBM 15%
medulloblastoma 15%
pituitary 5-10%
ependymoma 5-10%
optic nerve glioma <5%```

Question 16

perinauds syndrome

Answer 16

paralysis of upward gaze psudo argyll robertson pupilconvergence retraction nystagmuscolliers sign sun setting sign

Question 17

ependymoma management

Answer 17

spinal cord: maximal safe resection, if str give adj rt 50.4 graygrade 2/3: maximal safe resectionif spinal mri/csf +ve: csi 30-36gy+focal boost 54-60gy for local disease and 45gy for spine

Question 18

differential diagnosis of posterior fossa mass

Answer 18

medulloblastoma
ependymoma
astrocytoma and metastasis

Question 19

poor prognositic factor for medulloblastoma

Answer 19

male age <5 years
M1 disease

Question 20

survival rate of medulloblastoma

Answer 20

standard risk DFS 60-90%| high risk: 20-40% increased to upto 50-85% with adjuvant chemo

Question 21

Acute side of RT in CNS

Answer 21

Acute:
Hair:
Alopecia: alopecia starts at 7th day
Mucosa:
Erythema Edema Patchy mucositis Confluent mucositis
Eye:
Early:conjuntivitis Decreased tear drops Infection
Late:
necrosis in retina
Dry eye
Cataract
Optic nerve and optic chiasma damage at >50 gy
CNS:
Acute:
effect depends on edema, dose, site etc
Acute: within 6 weeks-
Pretreatment deficit worsens due to peritumoral edema-
Fatigue,
headache,
drowsiness-
Mild dermatitis-
Nausea, vomitting, more in post fossa brain irradiation-
Otitis externa-
Mucositis,
esophagitis due to exit dose
nazir sir
obliterating end arteritis
direct damage to nerve cell, blood cell, glial cell
narrowing of small blood vessel

Question 22

Sub acute side effect of RT in CNS

Answer 22

Sub acute
That develop during 6 week to 6 months.due to changes in capillary permeability and well as transient demyelination due to damage to oligodendroglial cells-
Headache-
Somnolence-
Fatigability-
Deterioration of preexisting deficits- The phenomenon of psuedo progression fits within the subacute toxicity time frame

Question 23

Late side effect of RT in brain:

Answer 23

Late sequale:
* 6 months to many years-
* Irreversible progressive nerve injury due to demyelination-
* Vascular injury necrosis-
* Radiation induced neuro cognitive damage
* Radiation necrosis: upto 3 years (differentiate by PET, MRS)-
* Diffuse leuko encephalopathy (CT+RT more common)-High tone hearing loss-
* Optic chiasm,
* nerve injury (>54 gy)-
* Hormone insufficiency (20gy)
* Spinal cord: L’Hermittes sign:
Nazir sir
moya moya syndrome

Question 24

Indication of SRS

Answer 24

Clinical indication:
• SRS for single brain metastases:
o Dose <2cm is 24 gy, <2-3 cm is 18Gy, >3-4 cm is 15Gy
• Acoustic neuroma
• Pituitary adenoma
o Nonfunctioning adenoma 12-20gy, functioning adenoma 15-30gy
• Skull based meningioma
o 12-14 gy
• Arteriovenous malformation and cavernous hemangioma
o Dose tumor size <4cm is 20-25 Gy
• Trigeminal neuralgia
o Dose 70-90 gy
• Parkinson disease

Question 25

Name some malignancies where CSRT is required

Answer 25

• medulloblastoma: average, high risk
• Ependymoma
• Pineoblastoma
• Primary cns lymphoma with leptomeningeal involvement
• Choroid plexus carcinoma with spinal metastatis
• Supratentorial PNET
• Intracranial germ cell tumor (Germinoma)
• Leukemia/ lymphoma (with CNS involvement)

Question 26

What is suggestive of a malignant tumor on MR spectroscopy?

Answer 26

Show Answer
Increased choline (cell membrane marker), low creatine (energy metabolite), and low N-acetyl-aspartate (a neuronal marker) are suggestive of malignancy on MR spectroscopy.

Question 27

Classification of glial tumor

Answer 27

Gr1: pilocytic astrocytoma
Gr2: diffuse astrocytoma, gemistrocytic astrocytoma
Gr3: anaplasticvatrocytoma
Gr4: GBM

Question 28

What are the 5 negative prognostic factors for LGG as determined by EORTC 22844 and 22845? Pignatti criteria
Show Answer

Answer 28

Negative prognostic factors per the EORTC index:
1. Age>40yrs
2. Astrocytomahistology
3. Tumors ≥6 cm
4. Tumors crossing midline
5. Preopneurologicdeficits
(Pignatti F et al., JCO 2002)

Question 29

Median survival for AA and GBM

Answer 29

Aa: 3yrs
Gbm: 14 mos

Question 30

Name some supratentorial tumor

Answer 30

Glial tumor: low grade: astrocytoma
GBM
anaplastic astrocytoma
meningioma
oligodendroglioma
CNS lymphoma

Question 31

Name some infratentorial tumor

Answer 31

brain tumor located in cerebellum and brainstem, fourth ventricle
-medulloblastoma
-craniopharyngioma
choroid plexus papilloma
ependymoma
PNET etc

Question 32

Molecular marker affecting CNS

Answer 32

IDH 1/2 mutation
1P/19Q codeletion
TP53 mutation
ATRX mutation
TERT mutation