CNS Flashcards
What spinal level is end of cord?
L1/L2
What level is the end of the cord in children?
L3/L4
Spinal level of termination of thecal sac
S2
Describe the flow of CSF
- Lateral ventricle
- Foramen of munro
- 3rd ventricle
- Aqueduct of Silvius
- 4th ventricle
- Foramen of Luschka (lateral) and foramen of magendie (medial)
What are the contents of the cavernous sinus?
- Cranial nerve III, IV, V1, V2, VI
- Internal carotid artery
Which is the first CN usually damaged with cavernous sinus problem
CN VI
What CNS tumors associated with NF1?
Optic glioma
astrocytoma
What CNS tumors associated with NF2
Schwannomas
Meningioma
Astrocytoma
Ependymoma
What are the path hallmarks of glioblastoma
Nuclear atypia
Mitotic index
Endothelial proliferation
Necrosis
What is the spectroscopy signal of tumor
Increased choline
Decreased creatine and NAA
What is the spectroscopy signal of necrosis
Decreased choline
Increased lactate
How to make diagnosis of molecular GBM?
- Histologic grade II or III astrocytoma
- IDH wt
- One or more of the following features
- EGFR amplification
- +7/-10 whole chromoscome gain/loss
- TERT promoter mutation
What is first step for suspected HGG
Steroids if symptomatic
Maximally safe resection
What to look for on path report for HGG
- MGMT methylation status
- IDH status
- EGFR amplification
When should CRT start after surgery for glioblastoma
4-6 weeks
What is the recommended treatment for glioblastoma (non elderly)
- Maximally safe resection
- RT to 60 Gy with concurrent and adjuvant temodar
- Can discuss adjuvant TTF with patient which had improved OS
Dose of TMZ for concurrent CRT
75 mg/m2 daily (7d per week)
Dose of TMZ adjuvant
150 mg/m2 (cycle 1)
200 mg/m2 (cycle 2-6)
Dosed first 5 days of month for 28d cycles
How long does TTF have to be worn?
18+ hours a day
What is the algorithm for elderly GBM
- High KPS: Stupp
- Normal KPS: 40/15 with TMZ
- Borderline
- TMZ alone if methylated
- RT alone if unmethylated
- 40/15
- 25/5
- Low
- Bev alone (if symptomatic)
- Best supportive care
Best treatment for recurrent GBM
Enroll on clinical trial
Consider re-resection
Dose of bev for glioblastoma
10 mg/kg q2w
What is the best reRT dose
Enroll on trial
If off trial, 3.5 Gy x 10 to the contrast enhancement + 5 mm margin with bev if possible
What is median OS for glioblastoma with Stupp
15 months
23 months if MGMT methylated
12 months if unmethylated
What is highest tox of TMZ?
heme tox (7%)
What is the definition of elderly for glioblastoma?
Roa: 60
Perry (w TMZ): 65
What was the OS difference from TTF?
5 months
(21 months vs. 16 mos)
GBM volumes for Stupp
Fuse T1 post MRI and FLAIR
Contour T1post enhancing disease
Expand by 1.5 cm, adjust to cover all FLAIR+ disease and adjust off critical structures and natural anatomic boundaries
PTV margin of 0.5
Coverage target for HGG
>95% PTV receives 100% of dose
What hotspot is acceptable for HGG
<107%
Spinal cord tolerance
<50 Gy
Brainstem tolerance (conventional fx)
<55 Gy
Optic chiasm/nerve constraints (conventional)
<54 Gy
Retina constraint (conventional fractionation)
<45 Gy
Lens constraint (conventional fractionation)
Mean <7 Gy
Target coverage for hypofractionated glioblastoma
Heterogeneity within 5% (hotspot < 105%, cold spot > 95%)
OAR constraints for hypofractionated glioblastoma
Brainstem, optics, eye, retina
All should not receive more than 100% of Rx’d dose
Lens mean <4 Gy
What is expected OS for TMZ alone for glioblastoma
8 months
What is expected OS for RT alone for glioblastoma
5 months
What is the median survival after reRT and bev?
10 months
How often does progression occur on first post RT scan?
50%
Of the patients who progress early, how many are true POD?
50%
DO NOT CHANGE MGMT AFTER FIRST SCAN
For anaplastics, what should be asked about path report?
- Path - oligo or astrocytoma
- IDH status (trumps all)
- 1p19q codel status
What is IDH?
enzyme in Krebs cycle
What is PCV?
- Procarbazine
- CCNU (lomustine)
- Vincristine
How is PCV administered?
Procarbazine and Lomustine are oral
Vincristine is IV
How long is a cycle of PCV?
6 weeks
What is the pCV schedule?
Day 1- vincristine and lomustine
D1-10: procarbazine
32 days off
What percentage of anaplastic gliomas are enhancing?
2/3
How should anaplastic gliomas be classified
- If IDHwt –> molecular glioblastoma
- If IDHmut
- 1p19q codel –> molecular oligo
- 1p19q intact –> molecular astro
How to approach IDHwt anaplastic gliomas?
Would treat like glioblastoma (on protocol)
60 Gy in 30 fractions with concurrent adjuvant TMZ
How to treat IDHmt anaplastic gliomas?
- Maximal safe resection
- If 1p19q codel –> RT to 59.4 Gy –> adjuvant PCV x 6 cycles
- If 1p19q non-codel –> RT to 59.4 –> adjuvant TMZ
What is the RT dose for anaplastic gliomas
59.4 Gy in 33 fractions of 1.8 Gy
How should chemo be given for anaplastic astro?
If IDHwt –> concurrent/adjuvant
If IDHmt –> adjuvant only (per CATNON)
What is the expansion for anaplastic gliomas
Cavity + 1.5 cm, include FLAIR
0.5 cm PTV margins
What is expected OS for anaplastic oligo?
14 years
What is expected survival for anaplastic astro, IDH mt
6 years
What are the path characteristics of pilocytic astrocytoma
Rosenthal fibers
Located in cerebellum or 3rd ventricle
Generally pts < 25 years old
What LGG patients are considered high risk?
Age > 40
STR
What are the negative prognostic features of LGG per EORTC
SATAN
- Size > 6 cm
- Age > 40
- Tumor crossing midline
- Astrocytic component (1p19q intact)
- Neuro deficits preop (including seizures)
Approach for high risk LGG
- Maximal safe resection
- RT to 54 Gy in 30 fractions
- If 1p19q codel –> adjuvant PCV x 6 cycles
- If IDH mt but 1p19q intact –> adjuvant TMZ
- If IDH wt –> consider concurrent and adjuvant TMZ
Approach to low risk LGG
Maximal safe resection –> observation
Reminder: age <40, GTR
Approach to pilocytic astro
Maximally safe surgery
RT only if recurrence or biopsy
RT dose for pilocytic astro
1.8 x 28 = 50.4 Gy
Contouring for LGG
Contour FLAIR on MRI
CTV = 1 cm expansion, respect boundaries
PTV = 0.5 cm
What is 10 year OS for grade II oligo
75%
What is 10 year OS for grade II astro
45%
What percentage of the grade II tumors undergo malignant transformation?
50%
Does RT increase rate of malignant transformation for LGG?
No
What is the radiographic appearance of PCNSL
Homogeneous, multifocal
Periventricular
Crossing corpus callosum
What stage is PCNSL
Ann Arbor IE
What is the workup for PCNSL
Do not start steroids
MRI brain
MRI spine
PET CT
Testicular US for men >60
Other workup needed for PCNSL
- LP
- Eye exam
- Brain biopsy if LP non diagnostic
Necessary labwork for PCNSL
- CBC
- CMP
- LDH
- EBV
- HIV
- Toxo
How to approach if bx negative on steroids
Hold steroids
Re-biopsy on progressions
Treatment approach for fit patients with PCNSL
- R-MVP x 5 cycles
- If CR –> reduced dose WBRT –> 2 cycles Ara-C
- If PR –> 2 more cycles RMVP
- If CR after 7 cycles –> rdWBRT
- If PR after 7 cycles –> 45 Gy WBRT
What is R-MVP
Rituximab
High dose MTX
Vincristine
Procarbazine
How often is a cycle of RMVP
q2w
What is the dose of MTX for PCNSL
3.5 mg/m2
What should be treated for PCNSL
WBRT
Include posterior 1/3 of orbit (bb at lateral canthus with half beam block)
Cover to C2/C3
If ocular involvement, include bilateral orbits
Dose of WBRT for PCNSL
If CR to RMVP = 23.4 (1.8 x 13)
If PR to RMVP = 45 (1.8 x 25)
What is a low risk meningioma?
New grade 1 (any extent of surgery)
What is an intermediate risk meningioma?
- Recurrent grade I
- Grade II with GTR
High risk meningioma
- Recurrent grade 2
- New grade 2 s/p STR resection
- New or recurrent grade 3 (any extent of surgery)
Recommended treatment for low risk meningioma
Surgery –> observation
Recommended treatment for intermediate risk meningioma
Surgery –> 54 Gy
Recommended treatment for high risk meningioma
Surgery –> 54 Gy with boost to 60 Gy to high risk region