A brain tumor is a mass or growth of abnormal cells in the brain or spinal cord. Many brain tumors are able to disrupt the function of the brain. Others, however, are less harmful.
Brain tumors are either malignant (harmful) or benign (nonharmful). By definition, malignant tumors are more aggressive than benign tumors.
In benign tumors, the mass of abnormal cells does not contain cancer cells. Benign brain tumors grow slowly and tend not spread from the original growth site. They are also more common than malignant tumors.
In fact, according to the American Brain Tumor Association (ABTA), around two-thirds of all new brain tumors are benign.
Malignant brain tumors contain cancer cells and tend not to have clear borders. These can grow rapidly and spread to other parts of the brain, which makes them more dangerous.
The American Cancer Society (ACS) group the statistics for brain tumors with those for tumors of the spinal cord. They estimate that healthcare professionals will diagnose up to 23,820 malignant primary brain and spinal cord tumors in 2019.
In this article, we look at both main categories of brain tumor, their symptoms, and how to treat them.
Doctors may also refer to a tumor based on the site from which the cells originated.
If the tumor began in the brain, for example, it is a primary brain tumor. If it began in another part of the body and spread to the brain, it is a secondary (or metastatic) brain tumor.
Each type of tumor has a range of different characteristics and subtypes, and a tumor may consist of more than one type of cell.
In 2016, the World Health Organization (WHO) officially reclassified all types of brain and spinal cord tumor. There are now over 120 types of brain and spinal cord tumors that affect different types of cell.
Acoustic neuroma or vestibular schwannoma
This type of cancer forms on the sheaths that protect nerves. It often affects the nerves involved in hearing.
These benign tumors may form at the base of the spine or skull, or near the pituitary gland. However, they may become malignant chondrosarcomas.
Central nervous system lymphoma
This is a highly aggressive type of cancer that affects the immune cells in the lymph nodes. It is most common in people ages 60–80, but it is becoming more common in young adults.
These tumors develop near the optical nerve, at the base of the brain, and near the pituitary gland. They develop from cells in the pituitary gland.
Germ cell tumors
These develop from germ cells, mainly in people around 11–30 years of age. They can be either benign or malignant.
A glioma is a tumor that starts in the supportive tissue of the brain. These affect three different types of cell: astrocytes, ependymal cells, and oligodendrocytes.
They can develop in several locations across the brain and nervous system.
These are overgrowths of blood vessels in the skin or internal organs. In the brain, there are two main types.
Hemangioblastomas are slow growing, benign tumors. Hemangiopericytomas develop in the meninges, the membrane of the brain, and can spread to distant organs such as the lungs.
These are masses that grow from fatty tissue. They are benign and very rarely cause symptoms or health problems.
This is more common in children. Medulloblastomas develop in embryonic cells early as an embryo develops.
They always develop at the lower portion of the brain at the back. They usually spread, but rarely outside of the brain and spinal cord.
These usually develop inward from the protective layer that covers the brain and spinal cord, applying pressure.
They account for around one-third of all tumors that start in the brain. Most are noncancerous.
This is a tumor of the nerve fibers. These develop due to a genetic condition called neurofibromatosis.
Neuronal and mixed neuronal-glial tumors
These develop from groups of nerve cells called ganglion cells. They are benign and grow slowly.
Pineal and pituitary tumors
These develop on glands that play essential roles in hormone secretion.
Primitive neuroectodermal tumor
These closely resemble medulloblastomas under a microscope but grow on a different part of the brain. They are rare but highly malignant and tend to spread.
Symptoms of brain tumors vary depending on the type of tumor and its location.
The following symptoms may occur slowly and gradually get worse. They may also develop quickly in the form of a seizure.
Common symptoms of brain tumors include:
- persistent headaches
- problems with vision
- nausea, vomiting, and general drowsiness
- issues with short term memory
- speech problems
- coordination issues
- personality changes
However, some people experience no symptoms at all.
According to the ACS, around half of people with a brain tumor experience persistent headaches. The ACS also say that up to half of all people with a brain tumor experience a seizure at some point.
To diagnose a brain tumor, a doctor may carry out a neurological exam. This is a test of the nervous system.
During this test, they will check various functions for problems with possible links to a brain tumor.
These functions include:
- limb strength
- hand strength
- skin sensitivity
- mental agility
After these tests, a doctor may then schedule additional exams, including:
- CT scan: This produces a detailed X-ray image of the brain.
- MRI scan: This uses a strong magnetic field and radio waves to provide a detailed image of the brain.
- EEG: During this test, a healthcare professional will attach electrodes to a person’s head to check for any abnormal brain activity.
If a doctor suspects a brain tumor, they will usually request a biopsy.
During a biopsy, a healthcare professional will remove a piece of the tumor. They will then send it to a laboratory for testing. The tests aim to identify whether or not the tumor is cancerous.
According to the ACS, most brain tumors do not have links to any known risk factor.
The ACS also say that most people with brain tumors do not have a family history of the condition. However, some familial cancer disorders can contribute to certain types of brain tumor. These include:
- neurofibromatosis 1 and 2
- tuberous sclerosis
- von Hippel–Lindau disease
- Li–Fraumeni syndrome
People with weaker immune systems, such as those with late stage HIV, might also have an increased risk of brain tumors.
There are several factors that healthcare providers consider when deciding how to treat brain tumors.
They will work closely with the patient to inform them of their treatment options, which will allow them to choose the most suitable treatment.
Factors they consider include:
- the person’s age
- their general health status
- their medical history
- the location, size, and type of tumor
- the risk of the tumor spreading
- the person’s tolerance for certain treatments
The following are some of the most common treatment methods for brain tumors.
Surgery is usually the first method of treatment for brain tumors. The surgeon will aim to remove as much of the tumor as possible. They will try to do so without damaging any of the healthy brain tissue that surrounds the tumor.
Sometimes, the surgeon may not be able to remove the entire tumor. If this is the case, they may surgically remove as much of it as possible before using radiation or chemotherapy to remove the rest.
It is important to note that surgery is not effective against tumors that are deep in the brain tissue or those that have spread across a wide area of brain tissue.
Surgery may also help provide a tumor sample for biopsy or to relieve symptoms such as pressure on the brain.
The aim of radiation therapy is to destroy a brain tumor or prevent its growth. To do this, healthcare providers will administer beams of intense energy to the patient’s brain from an external source. This causes the tumor to shrink. The patient’s immune system then takes action on the destroyed cells.
However, radiation cannot distinguish between tumorous cells and healthy cells. It can damage both types.
Different forms of radiation therapy can reduce damage to healthy tissue. This includes three dimensional conformal radiation therapy (3D-CRT), during which a healthcare provider aims several weak radiation beams at the tumor from different angles.
As the beams are weaker, they damage very little noncancerous tissue. However, they cause more damage where they meet at the site of the tumor.
Radiosurgery is the common name for stereotactic radiosurgery (SRS). SRS is a specialized form of radiation therapy and is not a surgical procedure.
SRS allows a healthcare provider to administer a precise dose of radiation in the form of an X-ray beam. They can focus the radiation only on the area of the brain where the tumor is present. This reduces the risk of damage to healthy tissue.
A healthcare provider may prescribe steroids to a person with a brain tumor. Although these do not directly treat the tumor, they can help an individual with some of the symptoms and discomfort. They might also improve overall well-being.
Antiseizure medications can help reduce the frequency of seizures. Also, if a tumor is affecting the function of the pituitary gland, a person might need hormone supplements.
Chemotherapy entails the use of specific drugs to treat brain tumors. A cancer specialist may recommend these drugs for malignant tumors that are more serious.
These drugs stop the brain tumor from growing and work by preventing the tumor cells from duplicating. Chemotherapy can also artificially cause the tumor cells to begin the process of dying as a noncancerous cell would.
However, many chemotherapy drugs cannot cross the blood-brain barrier and would be unlikely to reach a brain tumor. People with some brain tumors may benefit from the administration of chemotherapy drugs into the cerebrospinal fluid.
Healthcare providers often prescribe chemotherapy to support surgery or radiation therapy. However, for brain tumors such as lymphoma and medulloblastoma, chemotherapy can be an effective treatment on its own.
In the United States, the 5 year survival rate for people with brain tumors varies depending on the person’s age, the tumor type, and other factors.
This rate compares the likelihood of a person who has a brain or spinal cord tumor surviving for 5 years after diagnosis with that of a person who does not have cancer.
For example, a person with ependymoma has a 92% chance of surviving if cancer develops when they are 20–44 years of age. It drops to 86% if a doctor diagnoses this type in a person who is 55–64 years of age.
For the same age ranges, glioblastoma has a 5 year survival rate of 19% and 5%, respectively.
However, the National Cancer Institute advise that in 2009–2015, 32.9% of people with cancer of the brain or nervous system survived for 5 years or longer, considering all types.
However, given the range of types, only a doctor will be able to give a clear indication of the likely outlook.
After a brain tumor diagnosis, it can be a very stressful time. The ABTA offer care and support to people with brain tumors. They are contactable toll free at (800) 886-ABTA.
Where do brain tumors spread if they move outside of the brain and central nervous system?
The majority of brain tumors do not spread outside of the brain. However, some types of tumor spread to other parts of the central nervous system, such as the spinal cord.Seunggu Han, MD Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.