Brain Tumor Types
Brain tumors can be categorized into two main types:
- Primary Brain Tumors:
- Originate within the brain. They can be benign or malignant. They're named for the type of cells or brain region where they develop.
- Metastatic Brain Tumors:
- These tumors originate from cancer elsewhere in the body and spread to the brain. Common cancers that metastasize to the brain include melanoma, lung, and breast cancers. Management of metastatic brain cancer requires addressing the primary tumor that originated elsewhere in the body and the secondary brain lesion.
Primary Brain Tumors
- Diffuse Gliomas:
- Arise from glial cells (astrocytes or oligodendrocytes) that make up > 90% of brain cells and are typically seen in cerebral hemisphere lobes such as frontal, parietal, or temporal lobes in particular. They can spread to different parts within the brain or less commonly the spinal cord or fluid spaces within brain/spine, but almost never spread to the body.
- Astrocytomas:
- Develop from astrocytes. Have 3 different degrees of aggressiveness (Grades 2, 3 and 4) and molecular make-up (e.g. have mutation in IDH gene or not). Generally, grade 2 and 3 are seen in younger patients (< 40 years old) while grade 4 astrocytomas are seen in older patients.
- Glioblastomas (GBM):
- The most common type of brain malignancy in adults. There are ~ 14,000 new GBM cases diagnosed every year in the US. These fast-growing cancers do not have IDH gene mutation and need surgery, radiation and chemotherapy.
- Oligodendrogliomas*:
- Develop from oligodendrocytes and have 2 different grades (2 vs. 3). They are generally less aggressive than astrocytomas and seen in younger patients, but they too may need surgery, radiation, and chemotherapy.
- *As of August 2024, IDH-mutated astrocytomas and all oligodendrogliomas are eligible for a new targeted therapy that works against the IDH mutation called vorasidenib which may help them delay the use of radiation.
- Meningiomas:
- Rise from the meninges, the sheath of cells that surround the brain. They are the most common primary brain tumor, with ~ 170,000 new cases per year. Their degree of aggressiveness is based on their grade. Most (80%) of them are benign or grade 1 and can be treated by surgery alone with a low recurrence rate. Grade 2 and 3 meningiomas may need radiation after surgery and infrequently chemotherapy too.
- Primary CNS Lymphoma:
- Arise in the brain, eyes, cerebrospinal fluid, or even spinal cord. They are malignant tumors diagnosed by biopsy and subsequently treated by a chemotherapy regimen of 3–4 drugs followed by a bone marrow transplant. Radiation may be needed over time.
- Pituitary Tumors:
- Arise from the pituitary gland within the brain and seen in younger patients. Can be benign (adenomas) or malignant (carcinoma). Some of them (prolactinomas) can be diagnosed by checking the blood for hormone levels and are treated by medication only. Others may need surgery/biopsy for diagnosis, followed by radiation and/or chemotherapy.
- Other:
- Less common brain tumors exist including pilocytic astrocytoma, ganglioglioma, hemangioblastoma, and are treated surgically with infrequent need for radiation or chemotherapy.
