OncologyTier 2Disease (DEADMAN)

Cerebral neoplasms

Description

Brain tumours are classified as primary (arising from brain/meningeal tissue - gliomas, meningiomas, primary CNS lymphoma) or secondary/metastatic (spread from a systemic primary) - metastatic disease is substantially more common overall

Brain metastases occur in a substantial proportion of patients with advanced cancer, most commonly from lung, breast, melanoma, renal cell, and colorectal primaries; among primary CNS tumours, glioblastoma is the most common and most aggressive in adults, meningioma the most common overall (usually benign)

Gliomas arise from glial cells, graded by WHO classification (increasingly incorporating molecular markers - IDH mutation status, 1p/19q co-deletion - alongside histology, since these carry independent prognostic and predictive significance)
Meningiomas arise from arachnoid cap cells - typically slow-growing, often incidental, causing symptoms through mass effect rather than invasion
Metastases seed via haematogenous spread, often at the grey-white matter junction (where vessel calibre narrows, trapping emboli) and are frequently multiple

MRI brain with contrast is the primary imaging modality - characteristic patterns help distinguish tumour types (ring-enhancing lesions, multiplicity, location) though tissue diagnosis is often still needed
Presentation reflects location and mass effect/raised ICP: focal neurological deficit, seizure (especially new-onset in an adult), headache with red-flag features, personality/cognitive change
Biopsy or resection provides definitive histological (and increasingly molecular) diagnosis; a solitary lesion in a patient with no known primary still requires a search for an occult systemic primary if metastasis is suspected radiologically

Meningioma - observation for small asymptomatic lesions; resection +/- radiotherapy for symptomatic/growing lesions
Glioma - maximal safe resection followed by radiotherapy +/- chemotherapy (temozolomide), tailored by grade and molecular markers
Brain metastases - management depends on number/size and systemic disease control: stereotactic radiosurgery for a limited number of lesions, whole-brain radiotherapy for extensive disease, surgery for a large/symptomatic solitary lesion, alongside systemic therapy for the primary cancer
Corticosteroids (dexamethasone) reduce peritumoural oedema and symptoms rapidly, used as a bridge to definitive treatment

Lung cancer, breast cancer, melanoma (disproportionately high propensity for brain metastasis relative to its incidence), IDH-mutant vs wildtype glioma biology

Prognosis varies enormously by tumour type and molecular subtype - IDH-mutant gliomas have substantially better prognosis than IDH-wildtype (glioblastoma-like) tumours at a similar histological grade, reflecting why molecular classification has become central to modern management

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