Brain Metastasis - most common brain tumour seen clinically (~1/3 of all adult brain tumours; 15-30% of cancer pts present /w cerebral metastases); Well circumscribed, often at grey-white matter junction. hematogenous spread most common.
most common sources : lungs, breast
other sources : kidney, thyroid, stomach, prostate, testis, melanoma
Primary Sources of Metastatic Brain Tumours
Lung 44%
Breast 10%
Kidney (RCC) 7%
GI 6%
Melanoma 3%
Location
80% are hemispheric, often at grey-white matter junction or junction of temporal-parietal- occipital lobes (likely emboli spreading to terminal MCA branches)
Investigations
identify primary tumour
metastatic work-up (CXR, CT ОБП/ОГК, abdominal U/S, bone scan, mammogram)
CT with contrast → round, well-circumscribed, often ring enhancing, ++ edema, often multiple
MRI more sensitive, especially for posterior fossa
consider Bx in unusual cases, or if no primary identified
Treatment
Medical
phenytoin (or levetiracetam) for seizure prophylaxis if patient presents with seizure
dexamethasone to reduce edema given with ranitidine
chemotherapy (e.g. small cell lung cancer)
Radiation
stereotactic radiosurgery: for discrete, deep-seated/inoperable tumours
multiple lesions: use whole brain radiation therapy (WBRT); consider stereotactic radiosurgery if <3 lesions
post-op WBRT is commonly used
Surgical
single/solitary lesions: use surgery + radiation
Prognosis
median survival /wo Tx once symptomatic is ~1 mo, with optimal treatment 6-9 mo but varies depending on primary tumour type