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What is brain cancer?
A brain tumor is a growth of abnormal cells in or around the brain. Some are benign (slow and non-invasive) and some are malignant (cancerous). Because the brain controls everything we do, even a small tumor can cause symptoms by pressing on nearby tissue. The most common aggressive primary brain cancer in adults is glioblastoma. Tumors are graded by how abnormal the cells look under a microscope rather than by spread, because primary brain tumors rarely travel outside the brain.
The main types
Doctors group brain cancer by where it starts and how it behaves:
| Type | What it means, simply |
|---|---|
| Glioblastoma (GBM) | The most common aggressive adult brain cancer (a grade 4 glioma), treated with surgery, radiation, and chemotherapy. |
| Lower-grade gliomas | Slower-growing tumors (grades 2-3) arising from the brain's support cells; often treated and monitored over years. |
| Meningioma | Usually benign tumors of the brain's lining; many are watched or treated with surgery and/or focused radiation. |
| Brain metastases | Cancer that spread to the brain from elsewhere (lung, breast, melanoma) — the most common brain tumors overall, often treated with stereotactic radiosurgery. |
Staging, in plain terms
Brain tumors are not staged 0-IV like other cancers because they rarely spread outside the brain. Instead, doctors assign a WHO grade (1 to 4) based on how abnormal and fast-growing the cells look, plus molecular markers (such as IDH and MGMT) that guide treatment and predict response.
| WHO grade (not TNM) | What it generally means |
|---|---|
| Grade 1 | Slow-growing and well-defined; often curable with surgery alone. |
| Grade 2 | Still relatively slow but more likely to come back or progress over time; watched closely. |
| Grade 3 | Anaplastic — actively growing and more aggressive; usually needs radiation and chemotherapy. |
| Grade 4 | Glioblastoma — the most aggressive grade, treated promptly with combined surgery, radiation, and chemotherapy. |
The standard of care
Brain Cancer is almost always treated by a team that may include a surgeon, a medical oncologist, and a radiation oncologist, combining therapies for the best result. The usual building blocks are:
Surgery
Removing as much tumor as safely possible (maximal safe resection) relieves pressure, confirms the diagnosis, and improves how other treatments work.
Radiation therapy
Targets remaining tumor cells after surgery — the backbone of treatment for malignant gliomas like glioblastoma.
Chemotherapy (temozolomide)
An oral chemo given with and after radiation. Surgery + radiation + temozolomide is the long-standing 'Stupp protocol' standard for glioblastoma.
Tumor Treating Fields (Optune)
A wearable device that uses low-intensity electric fields to slow tumor cell division, added to maintenance chemotherapy for glioblastoma.
How radiation treatment works
Radiation uses focused, high-energy beams to damage the DNA of tumor cells so they can no longer divide. Treatment is shaped precisely around the tumor to protect healthy brain tissue, vision, and memory centers. For brain metastases and small benign tumors, stereotactic radiosurgery concentrates the dose in a single accurate session. Each treatment is painless and takes only minutes; the most common side effects are temporary fatigue and some hair thinning in the treated area.
The main ways radiation is delivered for brain cancer:
Fractionated external-beam radiation
After surgery for glioblastoma, focused radiation is given over about 6 weeks alongside daily temozolomide, targeting the tumor bed while sparing healthy brain.
Stereotactic radiosurgery (SRS)
Delivers a single high, pinpoint dose to small, well-defined targets such as brain metastases or some meningiomas — no incision, often one session.
Tumor Treating Fields (TTFields)
Adhesive arrays worn on the scalp create alternating electric fields that disrupt cancer cell division; adding TTFields to chemo extended median survival in a phase III trial.
Latest studies shaping care
Care keeps improving — often toward getting the same excellent results with less burden on patients. A few developments:
Tumor Treating Fields (EF-14): Adding the Optune device to maintenance temozolomide extended median overall survival from about 16 to 21 months in newly diagnosed glioblastoma — one of the few advances to improve survival in decades.[1]
EF-14 phase III trial
The Stupp protocol, 20 years on: Surgery, radiation, and temozolomide remain the proven standard for glioblastoma; recent reviews emphasize refining timing and patient selection while newer trials test immunotherapy and gene therapy.[2]
Stupp protocol; Lancet Oncology review (2025)
Immunotherapy combinations: Trials such as EF-41/KEYNOTE-D58 are testing TTFields plus immunotherapy (pembrolizumab) with chemotherapy, exploring whether the immune system can be enlisted against glioblastoma.[3]
EF-41/KEYNOTE-D58 phase III trial
Common questions
Is a brain tumor always cancer? No. Many brain tumors, like most meningiomas, are benign. The grade and tumor type — not just its presence — determine how serious it is and how it's treated.
Will radiation affect my memory or thinking? Modern techniques are designed to spare memory and other key regions. Some people notice temporary fatigue or fogginess; your team monitors this and adjusts care to protect function.
What is the Optune device? It's a wearable cap that delivers gentle electric fields shown to slow glioblastoma growth. It's worn at home alongside chemotherapy and doesn't involve radiation or surgery.
References
Numbered sources for the studies cited above. Links open the primary publication on PubMed or the publisher’s site.