Brain cancer is the result of an overgrowth of abnormal cells in the brain. These cells clump together to form a mass called a tumor. Brain tumors can be malignant or benign. Malignant tumors are cancerous, and they grow much quicker than benign (or non-cancerous) tumors, so they’re much more dangerous. In this article, we’ll focus on cancerous brain tumors.
Types of Brain Cancer
There are more than 150 types of brain tumors. Gliomas are the most common type of cancerous brain tumor in adults - about 78% of adults who are diagnosed with a malignant brain tumor will have a glioma. Gliomas are named for the cells they arise from, called glia. Glia are connective tissue cells that support the central nervous system. There are several types of gliomas:
- Astrocytomas are the most common type of glioma. About 50% of people who are diagnosed with a glioma will have an astrocytoma. Astrocytomas develop from specialized glial cells called astrocytes. They regulate the brain’s electrical activity.
- Ependymomas account for 2-3% of gliomas. They arise from cells called ependymal cells, which play a role in cerebrospinal fluid production.
- Glioblastoma multiforme (GBM) or glioblastomas are uncommon in general, but they’re slightly more common among people in their 50s, 60s, and 70s. Glioblastomas are particularly aggressive. They’re made up of astrocytes and oligodendrocytes and can arise from less aggressive astrocytomas or oligodendrogliomas.
- Medulloblastomas are more common in children. They form at the base of the skull and usually spread to other parts of the brain or spinal cord. Medulloblastomas are considered high-grade tumors, but they typically respond well to treatment (radiation and chemotherapy).
- Oligodendrogliomas form from oligodendrocytes. Oligodendrocytes are cells that provide insulation to axons, or nerve fibers. Oligodendrogliomas are about twice as common in adults as they are in children.
Risk Factors for Brain Cancer
Anyone can get brain cancer, but some people face a higher risk. People at the highest risk for brain cancer are those who have a family history of brain cancer and those who have another type of cancer, like lung, breast, or skin cancer. Other risk factors include:
- Increased age
- Pesticide, herbicide, or fertilizer exposure across long periods
- A job that requires exposure to lead, plastic, petroleum, or rubber
- A previous diagnosis of Epstein-Barr virus or mononucleosis
People who were born with defects in certain genes are more vulnerable to environmental risk factors.
Signs & Symptoms of Brain Cancer
Many of the symptoms associated with brain cancer are also associated with less serious conditions that are much more common than brain cancer. The symptoms of brain cancer will vary based on the size and location of the tumor, but general signs include:
- Difficulty thinking, focusing, and articulating
- Changes in speech, vision, or hearing
- Behavioral and personality changes
- Dizziness and balance issues
- Facial numbness
If you believe you may have a brain tumor, speak to your doctor right away. Your doctor may start by ruling out more probable causes of your symptoms. When they’ve ruled out other possible diagnoses, your doctor may perform all or any of the following tests:
- Imaging tests, like CT scans, MRIs, and PET scans. These tests help doctors get a better look at your brain, and will allow them to assess the location, size, and shape of the tumor.
- If the doctor identifies an abnormal growth on the brain, they may need to carry out a biopsy to confirm it’s cancerous. A biopsy also helps the doctor grade the tumor.
Grading Brain Tumors
Brain tumors are graded differently than other cancers. Unlike other cancers, which are graded based on size, location, and spread, brain tumors are also graded based on cell type and feasibility of removal.
Brain cancer is staged from one to four:
- Grade 1: The tumor is slow-growing and doesn’t seem to be spreading. It may be possible to remove the tumor permanently.
- Grade 2: The tumor is slow-growing, but there’s a chance it’s spreading, and if removed, the cancer may come back.
- Grade 3: The tumor is growing quickly and seems to be spreading. The cells are very different from normal cells.
- Grade 4: The tumor is growing and spreading quickly. The cells are completely different from normal cells.
Surgery for Brain Cancer
When it’s feasible, removing the tumor is the preferred treatment for brain cancer. If the tumor is accessible and can be detached from surrounding tissue, the doctor will try to remove the tumor completely. If a grade 1 tumor is removed, it’s unlikely the cancer will come back. If a grade 2 tumor is removed, there’s a chance it’ll come back in the future.
Radiation Therapy for Brain Cancer
Radiation therapy uses high-energy radiation to kill cancer cells. Radiation can be aimed directly at the tumor, but if the tumor is likely to spread, the doctor will perform whole-brain radiation therapy to minimize the risk of spreading.
Chemotherapy for Brain Cancer
In chemotherapy, drugs are used to kill cancer cells. The drug that’s most commonly used to treat brain tumors is in capsule form. Only some types of brain tumors respond to chemotherapy.
Biologics to Slow Brain Tumor Growth
Drugs called biologics can be used to slow the growth of brain tumors. These drugs work by restricting blood flow to the tumor.
Survival rates for treated cancer vary and depend on the type of cancer and characteristics of the tumor, including size, location, and grade. Five-year survival rates range from 5% to 85%.
If you’ve been diagnosed with brain cancer, it’s best to discuss your concerns and feelings with your doctor and family members as soon as possible. Brain tumors are time-sensitive, so don’t delay treatment. If you feel you’d benefit from extending your support system, connect with the American Brain Tumor Association. You can call their CareLine at 1 (800) 866-ABTA.