Pediatric LGG Flashcards
Tuberous sclerosis genetics
VHL, Gorlin
What do NF-1 patients get
optic pathway gliomas, intracranial glioma, JPA
Describe the characteristics of NF-1 mediated tumors
Tumors tend to be low grade, slow-growing.
3x risk of vasculopathy and occlusion of the Circle of Willis (moyamoya syndrome)
What about RT in Nf-1 patients
3x increased risk of radiation-induced secondary
malignancy
What tumors do NF-2 patients get
bilateral acoustic neuromas, spinal ependymoma
What should primary tx be in patients with tumors and neurofibromatosis
Treat with vincristine/carboplatin and avoid radiation if possible
What is the workup in pediatric LGG
MRI, then max safe resection followed by
MRI 24-72hrs post-surgery
Describe the histolpathology
IDH-mutants, 1p/19q-codeleted = oligodendroglioma
1p19q intact = astrocytoma
Grading (WHO)
Grade I = noninfiltrative = pilocytic astrocytomas, pleomorphic xanthoastrocytoma,
subependymal giant cell astrocytomas, ganglioglioma
Grade II = infiltrative/diffuse = 1p/19q co-deleted oligodendroglioma; ATRX retained
Grade III = ATRX lost (astrocytoma)
What is the treatment paradigm
If initially nonresectable or to delay radiation therapy, then
First line = vincristine/carboplatin – delays radiation by 3 years on average
Second line = vinblastine, TPCV, vinorelbine, irinotecan/avastin are common agents
Surgery- max safe resection
Then RT
What are the RT doses and cvolumes
Radiation
o GTV = gross disease (T1+Gad and FLAIR) and cavity
o CTV5040-5400 = GTV + 5mm anatomically constrained
PTV= CTV+ 3mm
What factor must be considered in follow up?
Pseudoprogression is quite common in LGG. NOn enhancing tumors may become enhancing after RT and can mimic tumor progression
What are 5 year survival outcomes
5 yr OS = 80%
5 yr PFS= 65%
Describe the histological appearance of pilocytic astrocytomas
-Well circumscribed, cystic, intensely enhancing solid mural nodules
-Degenerative hyalinization of blood vessels cause their enhancement
-Demonstrate rosenthal fibers
What genetic pathway is commonly altered in piloctyic astrocytoma
RAS-RAF_MEK-ERK
What is the treatment paradigm for pilocytic astrocytoma
Max safe resection
Consider observation following resection even if microscopically positive margins
- chemotherapy if progressive disease
- also consider observation especially if NF-1 given that they may spontaneously regress
- If unresectable or they fail chemo, then RT
What type of chemotherapy is used for pilocytic astrocytoma
vincristine/ carboplatin
How long does the use of chemo delay RT by in pilocytic astrocytoma
By 3 years
Describe RT prescription
GTV- T1 post gad enhancing area, surgical cavity, any gross disease and T2 FLAIR
CTV- GTV+ 5 mm, respecting anatomical barriers
PTV- CTV+ 3 mm
What genetic pathway is commonly altered in pleomorphic xanthroastrocytoma
BRAF V600E mutations and CDKN2A
What genetic disease is associated with Subependymal giant cell astrocytomas
Tuberous Sclerosis
What is the common treatment paradigm of Subependymal giant cell astrocytomas
Observation if asymptomatic
If symptomatic, max safe resection and MTOR inhibitors
Avodi RT given high risk of secondary malignancy
What is the most common type of optic pathway glioma
pilocytic astrocytoma
When do optic pathway gliomas present
90% present before age of 20
75% present before age of 10
What is the
What is the most common symptom of optic pathway glioma
painless proptosis
