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Brain Cancer: Types, Statistics, and Key Facts

Primary Brain Tumors: Epidemiology and Classification

Brain cancer refers to malignant primary brain tumors (originating in brain tissue) or metastatic deposits. Primary malignant brain tumors are rare (~1.4% of all cancers) but disproportionately lethal.

Incidence and Mortality (US, CBTRUS/SEER)

  • Children (0–14): 2nd leading cause of cancer death (after leukemia). ~3,500 cases/year.
  • Adults: 8th leading cause of cancer death. ~25,000 cases/year.
  • Median age: 60 years (bimodal: pediatric and older adult peaks).
  • 5-year survival: ~36% overall (varies drastically by histology).

Major Primary Malignant Types (WHO Classification)

  • Gliomas (~80% of malignant primary):
    • Glioblastoma (GBM, WHO grade 4): Most common, aggressive; median survival 15–18 months.
    • Astrocytoma (grade 2/3), oligodendroglioma (grade 2/3), IDH-mutant vs. wildtype.
  • Embryonal tumors: Medulloblastoma (pediatric, cerebellar).
  • Ependymal tumors: Ependymoma (spinal > intracranial).
  • Pineal region tumors: Germ cell tumors, pineoblastoma.
  • Meningiomas: Usually benign (grade 1); atypical/anaplastic (grade 2/3) are malignant.
  • Primary CNS lymphoma: Diffuse large B-cell; immunocompromised or immunocompetent.

Metastatic Brain Tumors

10x more common than primary. Sources: lung, breast, melanoma, renal, colorectal. Multiple lesions typical.

Risk Factors

  • Ionizing radiation (therapeutic).
  • Genetic syndromes (Li-Fraumeni, NF1, NF2, tuberous sclerosis, VHL).
  • Immunosuppression (CNS lymphoma).
  • No established link to cell phones, aspartame, power lines.

Symptoms

  • Focal: Weakness, aphasia, visual field loss, seizures.
  • Generalized: Headache (worse AM, Valsalva), nausea/vomiting, cognitive change, personality shift.

Diagnosis and Treatment

  • MRI with contrast (gold standard).
  • Biopsy/resection for histology, molecular markers (IDH, 1p/19q, MGMT, H3K27M).
  • Treatment: Maximal safe resection → radiation ± chemotherapy (temozolomide for GBM).
  • Clinical trials critical for recurrent disease.

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