Brain Tumor — Types, Symptoms, Diagnosis & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

A brain tumor is an abnormal growth of cells within the brain or the central nervous system (CNS), either arising from brain tissue itself (primary brain tumor) or spreading to the brain from cancer elsewhere in the body (secondary/metastatic brain tumor). Primary brain tumors are classified by the WHO into grades 1-4 based on histological aggressiveness and molecular characteristics (2021 WHO CNS Tumor Classification integrates histology and molecular markers). Major categories include gliomas (arising from glial cells — astrocytomas, oligodendrogliomas, ependymomas, and glioblastoma multiforme/GBM — the most common and aggressive primary brain tumor with median survival of 14-16 months despite treatment); meningiomas (arising from the meninges — 90% benign WHO Grade 1, most common primary brain tumor in adults); pituitary adenomas; acoustic neuromas (vestibular schwannoma); medulloblastomas (most common malignant brain tumor in children); and primary CNS lymphoma. Brain metastases — cancers that spread to the brain from lung (most common), breast, melanoma, colorectal, and renal primaries — affect 10-30% of cancer patients and are significantly more common than primary brain tumors. Brain tumors account for 3% of all cancer deaths globally and disproportionately impact working-age adults.

The vast majority (95%) of primary brain tumors have no identifiable cause. Established risk factors include: ionising radiation exposure — the only definitively proven environmental risk factor; prior therapeutic cranial irradiation (used for childhood leukaemia, pituitary tumours) increases meningioma and glioma risk; rare genetic syndromes cause a small proportion of primary brain tumors: neurofibromatosis type 1 (NF1 — gliomas), neurofibromatosis type 2 (NF2 — bilateral acoustic neuromas, meningiomas, ependymomas), Li-Fraumeni syndrome (TP53 mutations — multiple malignancies including glioblastoma), Cowden syndrome (PTEN mutations), tuberous sclerosis (subependymal giant cell astrocytomas), and Von Hippel-Lindau syndrome (haemangioblastomas). Immunosuppression (HIV/AIDS, solid organ transplantation) dramatically increases the risk of primary CNS lymphoma. Age (glioblastoma most common in 55-75 years), male sex (higher glioma incidence), and Caucasian ethnicity are epidemiological associations. Critically, multiple large studies and meta-analyses have found NO significant association between mobile phone use and brain tumors, despite widespread public concern. Aspartame, power lines, and other commonly implicated exposures similarly lack credible epidemiological evidence.

Brain tumor symptoms depend on tumor location, growth rate, and degree of raised intracranial pressure (ICP). Generalised symptoms from raised ICP: morning headache (worse on waking, aggravated by Valsalva manoeuvre — coughing or straining), nausea and vomiting, visual changes (papilloedema, diplopia from cranial nerve VI palsy), altered consciousness, and — in advanced cases — Cushing's triad (hypertension, bradycardia, irregular respirations — brainstem herniation imminent). Focal neurological symptoms determined by location: frontal lobe (personality and behaviour changes, executive dysfunction, hemiparesis, expressive dysphasia); temporal lobe (memory disturbance, receptive dysphasia, complex partial seizures, visual field defects — upper quadrantanopia); parietal lobe (sensory loss, hemispatial neglect, apraxia, Gerstmann syndrome); occipital lobe (visual field defects — homonymous hemianopia); brainstem (cranial nerve palsies, long tract signs — difficulty swallowing, diplopia, facial numbness); cerebellum (ataxia, dysmetria, nystagmus, intention tremor). Seizures occur in 30-50% of patients with supratentorial tumors and are often the first presenting symptom — any adult presenting with a first seizure warrants urgent MRI. Hormonal disturbance is characteristic of pituitary tumors. Rapidly progressive symptoms with headache, drowsiness, and focal deficits suggest haemorrhage into a tumor — a neurosurgical emergency.

MRI brain with gadolinium contrast is the gold standard imaging investigation — far superior to CT for characterising brain tumors, showing edema, mass effect, and blood-brain barrier disruption (ring enhancement in GBM). CT head is performed urgently for acute presentations to identify hemorrhage, hydrocephalus, or midline shift. MR spectroscopy distinguishes high-grade tumor (elevated choline, reduced NAA) from radiation necrosis. FDG-PET and amino acid PET (11C-methionine, 18F-FET) assess metabolic activity and guide biopsy targeting. Stereotactic biopsy provides tissue diagnosis when surgical resection is not feasible. Molecular profiling is essential for WHO 2021 CNS classification: IDH1/2 mutation (defines astrocytoma vs glioblastoma — IDH-mutant gliomas have significantly better prognosis); 1p/19q codeletion (defines oligodendroglioma — responds better to chemotherapy); MGMT promoter methylation (predicts response to temozolomide in GBM — methylated MGMT has better prognosis); EGFR amplification, TERT promoter mutation, CDKN2A/B deletion. Lumbar puncture for CSF cytology if leptomeningeal metastasis or CNS lymphoma is suspected (not performed if raised ICP). For metastatic brain tumors: CT chest/abdomen/pelvis, PET-CT, and biopsy of the accessible primary site or brain lesion to identify the origin and guide systemic treatment.

Treatment is multimodal and tailored to tumor type, WHO grade, molecular profile, patient age, and performance status. Surgical resection: maximum safe surgical resection (maximising tumor removal while preserving neurological function) is the primary treatment for most accessible brain tumors. 5-ALA (5-aminolevulinic acid) fluorescence-guided surgery enables surgeons to visualise GBM under ultraviolet light, improving gross total resection rates and survival. Awake craniotomy with cortical mapping is used for tumors near eloquent areas (speech, motor cortex). Stereotactic radiosurgery (Gamma Knife, CyberKnife) treats small, deep tumors and brain metastases with high-precision single or few fraction radiation — ideal for acoustic neuromas and multiple brain metastases. Whole brain radiotherapy (WBRT) is used for multiple brain metastases though hippocampal avoidance techniques reduce cognitive side effects. Standard GBM treatment (Stupp Protocol): maximal resection followed by concurrent temozolomide and radiotherapy (60Gy in 30 fractions), then 6 cycles adjuvant temozolomide — achieves median survival of 14-16 months. IDH inhibitors (ivosidenib for IDH1-mutant; olutasidenib) are now approved for IDH-mutant gliomas. Bevacizumab (anti-VEGF) is used for recurrent GBM to reduce edema and improve quality of life. Steroid dexamethasone rapidly reduces peritumoral edema and improves symptoms — used while awaiting definitive treatment. For brain metastases: surgical resection for single/few large lesions; stereotactic radiosurgery for limited number (<4); systemic targeted therapy or immunotherapy if primary cancer has known driver (e.g., EGFR-mutant NSCLC — osimertinib crosses blood-brain barrier).

Untreated brain tumours cause progressive neurological deterioration from direct tissue invasion, peritumoural oedema, and raised intracranial pressure. Transtentorial herniation — downward displacement of brain tissue from mass effect — is life-threatening, causing coma and death without emergency neurosurgical intervention. Uncontrolled seizures from cortical irritation carry status epilepticus risk. Glioblastoma without treatment has a median survival of only 3 months. Post-treatment complications include radiation necrosis (5-10% after radiotherapy), neurocognitive decline from whole-brain irradiation, steroid-induced diabetes and immunosuppression, and surgical complications (haemorrhage, infection, DVT). Secondary hydrocephalus from CSF obstruction requires ventricular shunting. End-stage disease causes progressive loss of consciousness and autonomic function.

No modifiable lifestyle risk factors have been definitively identified for primary brain tumors, given the lack of evidence linking common environmental exposures to risk. Avoid unnecessary therapeutic cranial irradiation, particularly in children, unless clearly indicated — radiation doses and techniques should be optimised to minimise neurocognitive late effects and second tumor risk. Individuals with established hereditary predisposition syndromes (NF1, NF2, Li-Fraumeni, VHL, tuberous sclerosis) should be enrolled in structured surveillance programmes with periodic MRI imaging. For those with prior brain tumor treatment: regular MRI surveillance is essential to detect recurrence early — frequency depends on tumor grade and treatment; GBM surveillance MRI is typically performed every 8-12 weeks for the first 2 years. Maintain brain health through physical activity, cognitive engagement, and cardiovascular risk factor control — though no direct prevention evidence for brain tumors exists, overall CNS health benefits are established.

Go to the emergency department immediately for: a first-ever seizure in an adult; sudden severe headache that is 'the worst of your life' (possible hemorrhage into tumor or subarachnoid hemorrhage); rapidly progressive neurological weakness, speech problems, or confusion developing over hours to days; signs of raised intracranial pressure — persistent morning headache with vomiting, especially if worsening over days to weeks; sudden loss or blurring of vision; and any marked deterioration in alertness or consciousness. Do not delay — untreated raised intracranial pressure can lead to brainstem herniation and death. Contact your GP or neurology team urgently for new unexplained persistent headaches with a change in character, progressive weakness or numbness in one side of the body, personality or memory changes, persistent balance problems, or a new visual field defect. Any patient known to have a brain tumor who experiences significant symptom change or new neurological deficit requires urgent medical review and repeat MRI.