Brain tumours Flashcards
How common are primary brain tumours?
Incidence 8 per 100,000
10% neoplasms
16th most common adult cancer - disproportionate killer in young adults
2nd most common paediatric cancer below leukaemia
Less than 2% of all malignant tumours but 20% of childhood
Majority supratentorial in adults
In children - majority posterior fossa
Most gliomas - astrocytoma (85-90%), oligodendroglioma (5%)
How common are secondary brain tumours?
10x more common than primary brain tumours
Which cancers are secondary brain tumours most likely to metastasise from?
Non-small cell (1) Small cell (2) Breast (3) Melanoma (4) Renal cell (5) GI (6)
What are gliomas?
Neuroepithelial origin seen within hemispheres mostly but also cerebellum, brainstem and cord
Unknown cause
Associated with neurofibromatosis
Spread by direct extension and rarely metastasise outside CNS
What are the 2 types of gliomas?
Astrocytomas (85-90%)
Oligodendromas (5%)
What are astrocytomas?
Gliomas arising from astrocytes
Grades I-IV
Grade I grows slowly over many years
Grade IV (glioblastoma multiforme) causes death within several months
Usually benign in children and cerebellar
What are oligodenromas?
Most common in 40s-50s Arise from oligodendrocytes Grow slowly usually over several years Calcification common May have seizures WHO grade II All IDH-1 mutation positive
What are meningiomas?
More common in elderly and women
Benign and arise from arachnoid mater and may grow to large size usually over years pushing into brain
Close to skull - erode bone or cause local hyperstosis
Often occur along intracranial venous sinuses which they may invade - usually below tentorium
Common sites - parasagittal region, sphenoidal ridge, subfrontal region, pituitary fossa, skull base
What are neurofibromas?
Schwanomas
Solid benign tumours arising from schwann cells and occur principally in the cerebellopontine angle
May be bilateral in neurofibromatosis type 2
What are ependymomas?
Arise from ependymal cells
Line ventricles and spinal cord
What are craniophyaryngiomas?
Very often benign tumours
Often diagnosed in younger patients
What can increase your risk of brain tumour?
More common in affluent groups Ionising radiation Vinyl chloride Immunosuppression FHx
What is the WHO grading for primary brain tumours?
Grade I - good prognosis, often benign
Grade II - > 5 year prognosis, premalignant tumour
Grade III - prognosis of 2-5 year survival rate, cancer, malignant, active growth, and mitotic activity on microscope
Grade IV - < 1 year survival prognosis, most common phenotype, active growth, mitotic activity and necrosis, vascular proliferation, very malignant
What are the 2 pathways to malignant glioma?
Common
Less common
What is the common pathway to malignant glioma?
Especially in those under 50-60
Initial genetic error of glucose glycolysis
Mutation of isocitrate dehydrogenase I
Results in build-up of 2-hydroxyglutarate
Triggers genetic instability in glial cells and subsequent inappropriate mitosis - cancer