Benign brain tumors vs. cancerous brain tumors
Some tumors are benign (noncancerous), while others are malignant (cancerous). Benign brain tumors are more common, representing nearly two-thirds of tumors starting in the brain.
While both types of brain tumors can grow, interfere with critical brain functions and potentially threaten your life, there are important differences:
- Benign brain tumors:
- Grow slowly and do not usually return when taken out
- May not cause symptoms until larger
- Have clear borders, making removal easier
- Malignant brain tumors:
- Grow faster and invade surrounding brain tissue
- Lack clear borders
- Can occasionally spread to the spine and (rarely) to other body areas
Primary brain tumors vs. metastatic brain cancer
When tumors start in the brain, they are called primary brain tumors. More commonly, cancer spreads, or metastasizes, to the brain from another part of the body such as the lungs, breasts or skin.
The brain tumors formed by metastatic cancer are fast-growing and known as secondary brain tumors. These malignant tumors are typically treated based on where the cancer started. Learn more about our metastatic brain cancer treatment.
Gliomas: Astrocytomas, glioblastomas and oligodendrogliomas
The majority of primary brain tumors develop in glial cells, the “glue” that holds the brain together. There are various types of glial cells and gliomas that can form in them, including:
- Astrocytomas: These tumors develop from astrocytes, star-shaped cells that secure and assist nerve cells. The most aggressive primary brain cancers are a type of astrocytoma called glioblastoma, also known as glioblastoma, GBM or grade IV astrocytoma.
- Oligodendroglioma: These rare and slow-growing tumors start in cells called oligodendrocytes that produce a substance to protect nerves. They can be either malignant or benign.
Meningiomas form in the meninges, the thin tissue layers between the brain and the skull. These tumors typically are benign and grow slowly.
Schwannomas develop from Schwann cells, which help form the protective covering (sheath) for nerves. These tumors are often found on the vestibular nerve, which is responsible for balance and located in the inner ear near the brain. Since vestibular schwannomas can harm hearing, they are also called acoustic neuromas.
Tumors can form in the pituitary gland, which sits at the bottom of the brain. These tumors are often benign, but can still interfere with the gland’s hormone production.