Oncology (WM) Flashcards
What’s the mechanism of action of Temozolamide?
Temozolamide is an oral alkylating agent
The cytotoxic effect is due to adding an alkyl group (methyl is the smallest alkyl group) to DNA primarily at the O6 and N7 positions on guanine.
With reference to Temozolamide, what’s the significance of MGMT?
Temozolamide adds an alkyl group to DNA, most cells repair this damage using the protein O6-methylguanine-DNA methyltransferase. Temozolamide is more effective against tumours with subnormal MGMT activity. MGMT promotor methylation reduces MGMT activty.
What’s the difference in the relationship to the nerve between neurofibromas and schwannomas?
Schwannomas displace axons (centrifugal)
Neurofibrommas are unencapsulated and engulf the nerve of origin (centripetal)
What’s the incidence of NF1 and NF2?
1: 3000 live births (NF1)
1: 40,000 live births (NF2)
What’s are the gene product in NF1 and NF2?
neurofibromin (NF1)
schwannomin (NF2)
Where’s the gene locus for NF1 and NF2?
NF1 ch17
NF2 ch22
What are the 7 diagnostic features of NF1? (2 of more needed for diagnosis)
3 skin: >6 cafe au lait spots >2 neurofibromas (or one plexiform neurofibroma) Freckling (axillary or intertriginous) 3 head: >2 lisch nodules (iris hamartomas) Osseous abnomality (sphenoid dysplasia or thinning of long bone cortex) Optic pathway glioma: 1 other: First degree relative
What’s the function of neurofibromin?
It’s a negative regulator of the RAS oncogene
What are the diagnostic criteria for NF2?
Bilateral VS
OR
A combination of unilateral VS +/ first degree relative +/- 2 of meningioma, schwannoma, glioma, posterior subcapsular lens opacity, cortical wedge cataract
OR
multiple meningioma and two of the following
What is the effect of pregnancy of 8th nerve tumours?
It can accelerate the rate of growth
What is the classic clinical triad of tuberous sclerosis?
Seizures
Mental retardation
Facial angiofibromas
What’s the incidence of tuberous sclerosis?
1:6000 live births
Give a differential for benign skull lesions
Sclerotic:
Fibrous dysplasia
Osteoma
Intraosseous meningioma
Lytic: Epidermoid cyst Dermoid cyst Calvarial sarcoid Langerhans cell histiocytosis
Not easily classified above:
Ossifying fibroma
Paget disease
Haemangioma (osseous venous vascular malformation)
Give a differential for malignant skull lesions
Primary
Osteosarcoma
Chordoma
Chondrosarcoma
Secondary
Multiple myeloma
Mets
(All lytic except sclerotic mets)
What’s survival in GBM?
In the stummer study 5-ALA resection group
Total resection ~16.5 months
Partial resection ~12
What’ the survival benefit of temozamide + RTX and RTX alone?
Stupp with RTX + temo 14.6months (25% improvement)
vs 12.1 (10% improvement) RTX alone
What’s the stupp protocol?
5 days a week RTX for 6 week with temozolamide
(60Gy total)
then four week break then up to 6 further cycles (5 days one 23 days off)
What’s impact of 5-ALA on resection?
Improves complete resection 36%-65%
What’s second line chemo for GBM?
PCV (procarbazine, lomustine, vincristine)
What’s the evidence for resection LGG?
Jakkola cohort study 2017
6 years vs 14 years for intention to treat by surgical strategy
What are the oncological options for LGG?
If residual and oliogo –> PCV and RTX
Non-codeleted –> consider PCV and RTX
No residual –> active monitoring
If intractable seizure and progression –> also an indication for PCV and RTX
What are the grade I tumours?
Astrocytic: pilocytic SEGA Ependymal: subependymoma Myxopallipllary Neuronal and mixed neuronal-glial tumours: gangliocytoma (lhermitte duclos) reosetter forming DNET others Anything ganglio
Describe MRS changes in glioma
Gliomas - increase in choline, relative fall in NAA
creatine is middle value
How would you distinguish post fossa medulloblastoma, ependymoma and pilocytic astrocytoma on imaging? (1 classic feature of each)
Medulloblastoma - high density on CTH
Ependymoma - Grows through 4th ventricle foramina Pilocytic - nodule with cyst
How does meningioma grade affect recurrence?
3* grade 2
5* grade 3
What is 2 year control for acoustics with gamma knife vs microsurgery?
94% Gamma knife
97% surgery
Describe House-Brackman scale?
1 - normal 2 - normal at rest 3 - obvious but complete eye closure 4 - incomplete eye closure 5 - flickers 6 - no movement
What tumour markers do you send of for pineal region?
alpha fetoprotein
bHCG
PALP
(Also remember to image whole spine for seeding)
What’s the classification of germ cell tumours?
Geminoma (weakly bhCG+ve) Non-germinomatous germ cell tumours - embryonal carcinoma (AFP) - yolk sac tumour (AFP) - choriocarcinoma (bHCG) - teratoma - mixed germ cell tumour
Teratomas - don’t express markers
Pineal origin tumours
Grade I - pineocytoma
Grade II-III - intermediate differentiation
Grade IV - pineoblastoma
Describe approaches to pineal
Infratentorial supracerebellar Occipital transtentorial Stereotactic Endoscopic through third ventricle (Interhemispheric transcallosal - if predominantly within third ventricle)
What do you do for air embolism and what end tidal C02 changes occurs?
Fall in end tidal CO2
Flat
Flood field
Right side up if possible
100 percent 02
What’s the classification for middle cranial fossa arachnoid cysts?
Galassi
I-III (small, medium, large)
What are the criteria for brainstem testing?
Exclude reversible (drugs, electrolytes) Then GCS 3 No response to CO2 challenge Pupillary reflex Corneal reflex Caloric reflex (COWS) Gag reflex Cough reflex
What are features of acromegaly?
Large hands Sweaty palms Carpal tunnel syndrome Hypertension Prominent supra-orbital ridge Increased interdental spaces Large nose Macroglossia Prognathism Displaced apex beat OSA Increased risk of bowel Ca DM
How do you diagnose acromegaly?
glucose tolerance test
Give glucose and growth hormone should suppress
Describe the knosp classification?
0 - Intrasellar 1 - abutting cav sinus 2 - infiltrating cav sinus but not beyond carotid 3 - beyond carotid 4 - encasing carotid
