Brain Cancer, from the CureRays guide library.

Brain tumors form when cells in or around the brain grow abnormally; treatment combines surgery, radiation, and medicine, tailored to the tumor type.

What it is.

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.

How radiation treats it.

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 ways we can treat it.

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.

Questions we hear often.

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.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.