Neuro-oncology

Brain Tumor Basics - Skull Invaders

• Primary (originate in CNS) vs. Secondary (metastases; commonest overall brain tumors).
• Commonest Primary Adult Tumors (WHO CNS5):
  • Meningioma (most common overall primary, usually Grade 1-2)
  • Glioblastoma, IDH-wildtype (Grade 4, most common primary malignant)
  • Pituitary adenoma
• WHO 2021 Updates: Emphasizes molecular markers for classification & grading (CNS WHO Grades 1-4).
• Key Molecular Markers:
  • IDH1/2 mutations: Better prognosis in gliomas.
  • 1p/19q co-deletion: Hallmark of oligodendroglioma (Grade 2-3); predicts chemosensitivity & better prognosis.
  • MGMT promoter methylation: In glioblastoma, predicts better response to temozolomide.

⭐ Glioblastoma (CNS WHO Grade 4) is the most common and most aggressive primary malignant brain tumor in adults. Despite its name, it rarely metastasizes outside the CNS.

Clinical Features - Brain's Distress Signals

• Raised Intracranial Pressure (ICP):
  • Headache (worse morning/Valsalva), nausea/vomiting, papilledema.
  • Cushing's triad (HTN, bradycardia, irregular respiration) - late, ominous.
  • Altered sensorium, diplopia (CN VI palsy).
• Focal Neurological Deficits (FNDs) - Location Dependent:
  • Frontal: Motor weakness, personality Δ, Broca's aphasia (dominant).
  • Parietal: Sensory loss, neglect, apraxia.
  • Temporal: Seizures, memory loss, Wernicke's aphasia (dominant).
  • Occipital: Visual field defects (e.g., homonymous hemianopia).
  • Cerebellum: Ataxia, dysmetria, nystagmus.
  • Brainstem: Cranial nerve palsies, vital sign instability.
• Seizures:
  • Common presenting symptom; often focal onset, may generalize.
• Headache Red Flags (📌 SNOOP4):
  • Systemic symptoms, Neurologic deficits, Onset (sudden/new, esp. >50 yrs), Pattern change/Progressive/Papilledema/Positional/Precipitated by cough/Valsalva.

⭐ New-onset seizure in an adult is a brain tumor until proven otherwise.

Major Tumor Types - Rogues' Gallery

Treatment Strategies - Counter Attack

Key goals: Maximize tumor control, preserve neurological function, maintain quality of life.

• Surgery:
  • Maximal safe resection: Aim for gross total resection (GTR) if feasible.
  • Obtain tissue for diagnosis.
  • Relieve mass effect, ↓ Intracranial Pressure (ICP).
• Radiotherapy (RT):
  • Types: External Beam RT (EBRT), Stereotactic Radiosurgery (SRS).
  • Indications: Adjuvant post-surgery, primary for unresectable tumors, palliative.
• Chemotherapy:
  • Temozolomide (TMZ): Standard for Glioblastoma (GBM).
  • Steroids (e.g., Dexamethasone): Manage vasogenic edema. Dose: 4-8 mg IV/PO QID.
  • PCV (Procarbazine, Lomustine, Vincristine) for certain oligodendrogliomas.
• Targeted Therapy:
  • E.g., Bevacizumab (anti-VEGF) for recurrent GBM.
• Palliative Care: Integral for symptom management & QoL at all stages.

⭐ The "Stupp Protocol" for Glioblastoma involves concurrent Temozolomide and radiotherapy, followed by adjuvant Temozolomide, significantly improving median survival.

High‑Yield Points - ⚡ Biggest Takeaways

• Glioblastoma (GBM): Most common adult primary; butterfly glioma appearance.
• Pilocytic Astrocytoma: Most common pediatric primary; Rosenthal fibers, often cerebellar.
• Meningioma: Common in females; psammoma bodies, dural tail sign.
• Medulloblastoma: Malignant pediatric tumor (cerebellum); Homer Wright rosettes, radiosensitive.
• Ependymoma: Fourth ventricle (children), spinal cord (adults); perivascular pseudorosettes.
• NF2: Associated with bilateral acoustic schwannomas, multiple meningiomas, ependymomas.
• Metastases: Most common intracranial tumors overall; often from lung, breast, melanoma.