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📖 Glossary of Terms

Medical terminology explained in plain language

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Adjuvant therapy: Treatment given after the primary treatment (surgery) to kill remaining cancer cells. In GBM, this is the TMZ cycles after chemoradiation.
Anaplastic: Rapidly growing, aggressive. Anaplastic astrocytoma is grade 3, one step below GBM (grade 4).
Angiogenesis: Formation of new blood vessels. Tumors need blood vessels to grow. Anti-angiogenic drugs (like Avastin) try to starve tumors by blocking this.
Apoptosis: Programmed cell death. Normal cells die when damaged; cancer cells avoid this. Many treatments try to trigger apoptosis in cancer cells.
Astrocyte: A type of brain cell (glial cell) that supports neurons. GBM arises from these cells.

BBB (Blood-Brain Barrier): A protective barrier that prevents most substances from entering the brain from the bloodstream. Major obstacle to treating brain tumors — most drugs can't cross it.
Bevacizumab (Avastin): Anti-angiogenic drug that blocks VEGF. FDA approved for recurrent GBM. Improves symptoms but doesn't extend survival.
Biopsy: Removing a small tissue sample to examine under microscope. Used to diagnose tumor type when full removal isn't possible.

CAR-T therapy: Chimeric Antigen Receptor T-cell therapy. Patient's immune cells are modified to attack cancer. Promising for GBM but still experimental.
Concurrent therapy: Treatments given at the same time. In Stupp protocol, radiation and TMZ are given concurrently for 6 weeks.
Craniotomy: Surgery where part of the skull is removed to access the brain. Standard approach for GBM surgery.

Dexamethasone (Decadron): Steroid medication used to reduce brain swelling (edema). Very effective but has significant side effects.
Diffuse: Spread throughout, not contained. GBM is "diffuse" meaning cells spread into surrounding brain tissue, making complete removal impossible.

Edema: Swelling. Brain edema around tumors causes symptoms like headaches, confusion, weakness.
EGFR (Epidermal Growth Factor Receptor): A protein often overactive in GBM, promoting cell growth. Some treatments target EGFR.
Eloquent area: Brain regions controlling critical functions (speech, movement, vision). Tumors in eloquent areas are harder to remove safely.

GBM (Glioblastoma): Glioblastoma multiforme. The most aggressive primary brain tumor. Grade 4. Median survival 15-18 months with treatment.
Glioma: Tumor arising from glial cells (support cells of the brain). Includes astrocytoma, oligodendroglioma, and GBM.
Grade: How aggressive a tumor is. Grade 1-2 are low-grade (slow). Grade 3-4 are high-grade (aggressive). GBM is always grade 4.
Gross Total Resection (GTR): Complete visible removal of tumor on MRI. Best surgical outcome. Associated with longer survival.

IDH (Isocitrate Dehydrogenase): An enzyme. IDH mutation = better prognosis. Since 2021, IDH-mutant grade 4 tumors are NOT called GBM anymore (they're "astrocytoma grade 4"). True GBM is IDH-wildtype.
Immunotherapy: Treatments that help the immune system fight cancer. Includes checkpoint inhibitors, vaccines, CAR-T. Still largely experimental for GBM.
Infiltrating/Invasive: Growing into surrounding tissue. GBM is highly infiltrative — cells spread beyond the visible tumor, making cure impossible with surgery alone.

KPS (Karnofsky Performance Status): Scale from 0-100 measuring how well patient functions. 100 = normal. 70+ = able to care for self. Used to determine treatment eligibility.
Ketogenic diet: Very low carbohydrate, high fat diet that puts body in ketosis. Being studied for GBM because tumors depend on glucose.

MGMT (O6-methylguanine-DNA methyltransferase): DNA repair enzyme. If MGMT gene is methylated (silenced), tumor can't repair TMZ damage = better response to chemo. If unmethylated = poor TMZ response.
MRI (Magnetic Resonance Imaging): Primary imaging for brain tumors. Shows tumor location, size, and changes over time.
Multifocal: Multiple separate tumors. Worse prognosis than single tumor.

Necrosis: Dead tissue. GBM characteristically has necrosis at center. "Radiation necrosis" = brain tissue death from radiation (can mimic recurrence on MRI).
Neuro-oncologist: Cancer specialist focused on brain and spine tumors. Should be part of your care team.

Oncolytic virus: Viruses engineered to infect and kill cancer cells. PVS-RIPO (polio virus) and DNX-2401 are in trials for GBM.
Optune (TTFields): Tumor Treating Fields. Device worn on head that delivers electric fields to disrupt cancer cell division. FDA approved for GBM.

Palliative care: Care focused on quality of life, symptom management, and support. NOT the same as hospice. Can be provided alongside active treatment.
Progression: Tumor growth or spread. "Progression-free survival" = time before tumor grows again.
Pseudoprogression: MRI looks worse after radiation, but it's not actual tumor growth — it's inflammation/treatment effect. Usually happens 1-3 months after radiation.

Radiation (RT): High-energy beams that damage DNA, killing cancer cells. Standard for GBM: 60 Gy in 30 fractions over 6 weeks.
Recurrence: Tumor coming back after treatment. Nearly universal in GBM.
Resection: Surgical removal. "Extent of resection" = how much was removed (GTR, subtotal, biopsy only).

Stereotactic: Using 3D coordinates for precise targeting. "Stereotactic radiosurgery" = highly focused single-dose radiation.
Stupp Protocol: Standard treatment regimen for GBM: surgery → 6 weeks radiation with daily TMZ → TMZ cycles for 6-12 months. Named after Dr. Roger Stupp.

Temozolomide (TMZ, Temodar): Oral chemotherapy, standard of care for GBM. Works by damaging tumor DNA. Most effective if MGMT methylated.
TTFields (Tumor Treating Fields): See Optune. Electric fields that interfere with cell division. Adds ~5 months median survival.

VEGF (Vascular Endothelial Growth Factor): Protein that stimulates blood vessel growth. Bevacizumab blocks VEGF.

WHO Classification: World Health Organization brain tumor classification. Updated in 2021 — now requires molecular markers (IDH, etc.) not just appearance.
Wildtype: Normal, non-mutated. "IDH-wildtype" = no IDH mutation = true GBM = worse prognosis.