What is a Brain Tumor?
In the simplest sense, a brain tumor is a group of cells, sometimes also called an intracranial tumor, in or near the brain that grow abnormally. Often, these cells divide and multiply more quickly than normal cells, and they may live longer than normal cells. The result is an uncontrolled mass of tissue that may interfere with healthy tissues’ normal functioning in the body.
There are many different types of brain tumors–more than 150 by most counts–that behave differently, affect various tissues and likely stem from different causes. Although there are dozens of different kinds of tumors, they are grouped into two broad categories.
Primary Brain Tumors
Primary brain tumors begin their growth in the brain itself or the tissues immediately surrounding the brain. Primary brain tumors are further classified into two types depending on the types of brain cells that are affected:
- Glial tumors are comprised of glial cells, the cells that surround and support neurons in the brain.
- Nonglial tumors occur in parts of the brain not made up of glial cells. These tumors may affect blood vessels, neural tissue, glands, or other central nervous system structures.
Finally, primary brain tumors are categorized as either benign or malignant.
- Benign tumors are made up of non-cancerous cells that do not spread to other parts of the body or invade other surrounding tissues. Benign tumors may grow more slowly than malignant tumors, and they usually don’t grow back if they are removed. However, they are not necessarily harmless; their growth may harm surrounding tissues even without cancerous growth patterns.
- Malignant tumors grow uncontrollably and can invade and destroy other tissues. The cancerous cells of malignant tumors may also spread to other parts of the body via the blood or lymphatic system.
Metastatic Brain Tumors
Metastatic brain tumors do not originate in the brain itself but instead spread from other parts of the body to the brain or central nervous system, often via the patient’s circulatory system. Metastatic brain tumors are, by definition, cancerous and malignant.
Metastatic brain tumors are more common than primary brain tumors, with about 150,000 new cases diagnosed each year. Any cancer originating anywhere in the body can spread to the brain, but the most common cancers that eventually affect the brain include breast cancer, colon cancer, kidney cancer, lung cancer, and melanoma (skin cancer).
What Causes A Brain Tumor?
The root cause of a brain tumor is a mutation or damage in the genes that control the growth of affected cells. In a healthy cell, these genes prevent the cell from growing or reproducing too rapidly, and the genes can also determine the cell’s expected lifespan. In a tumor’s cells, the damage to the genes causes the cells to grow and reproduce rapidly, and the cells may live longer than usual.
As this rapid growth and reproduction continues, the cells grow into an abnormal mass. In some cases, the tumor produces chemicals that stop the body’s immune system from fighting the cancer, and the tumor cells may also trigger an increase in blood supply to support their growth.
The causes of the gene damage that produces a tumor likely differs between the various types of tumors, and in most cases, the causes are not well understood. The gene mutation that predisposes someone to develop a particular kind of brain tumor may be present at birth in some cases, but there are also probably external environmental factors that trigger the development of a tumor.
Researchers have not pinpointed factors that increase the risk of developing most types of brain tumors, but two situations do increase the risk of certain tumors.
- Family history. A small number of brain tumor types have been positively linked to a family history of these types of tumors or genetic conditions that increase the risk of developing the tumor.
- Radiation exposure. Exposure to certain powerful types of radiation, called ionizing radiation, has been linked to brain tumors’ development. Exposure to this type of radiation comes from sources such as treatment for other cancers and nuclear explosions, not more common sources such as microwaves or radio waves.
Is A Brain Tumor Hereditary?
For the most part, brain tumors (and the genetic changes that cause them) do not appear to be linked to inherited traits. Instead, researchers believe that most gene changes that cause tumors come from external environmental causes or changes within cells that occur at random and with no external trigger.
There are, however, links between some types of brain or central nervous system tumors and specific genetic syndromes that run in families. Examples of these syndromes include neurofibromatosis, tuberous sclerosis, Li-Fraumeni syndrome, and von Hippel-Lindau syndrome.
How Is A Brain Tumor Detected?
Brain tumors do not always present recognizable symptoms in their early stages of growth, and when symptoms do present, they may vary depending on the location and type of tumor and its growth rate.
Some common general symptoms of brain tumors include:
- Headaches, especially when the patient has no history of headaches or the pattern or severity of headaches changes
- Nausea or vomiting that doesn’t have another apparent cause
- Difficulty swallowing
- Dizziness or problems with balance
- Difficulty concentrating
- Blurred vision, double vision, or loss of peripheral vision
- Hearing problems
- Numbness or tingling in the face
- Loss of strength or movement in arms or legs
- Confusion or disorientation
- Personality changes
How Is A Brain Tumor Diagnosed?
Doctors may take several different diagnostic steps when they suspect that a patient may have a brain tumor.
- Neurological exam. A basic neurological exam will test a patient’s reflexes, balance, coordination, strength, vision, and hearing. The results of this exam may prompt a doctor to look further for a tumor’s presence, and it may give a clue to the affected part of the brain, if any.
- Imaging. Imaging technologies are non-invasive ways to look at brain tissue and possibly detect a tumor’s presence. Magnetic resonance imaging (MRI) uses a strong magnetic field to produce images of the brain and central nervous system. Computerized tomography (CT) scan may also be used to look for tumors. Positron emission tomography (PET) scans are less commonly used to detect brain tumors.
- Tests for other cancers. The possibility of a metastatic brain tumor may prompt a doctor to look for cancer in other parts of the body using lab tests or imaging exams.
- Biopsy. Some tumors may be unidentifiable through imaging or other non-invasive means. In these cases, doctors may require a biopsy, in which a sample of the tumor is removed and analyzed by a pathologist. The biopsy might be conducted with surgery or, if the tumor is in a particularly hard-to-reach area, using a needle guided by imaging technology.
A pathologist’s examination of the tissue sample will indicate whether the tumor is malignant or benign and will likely suggest the best treatment course.
How Is A Brain Tumor Treated?
The type of treatment plan that will work best for a brain tumor depends on the type of tumor, its location, size, the overall health of the patient, and other factors. Different treatment options may be used alone or in combination, and the treatment plan may change depending on how the tumor reacts to the initial treatment.
The most direct way to treat a brain tumor is to remove as much of it as possible with surgical intervention. Typically, the surgery involves opening the skull and removing the tumor while being careful not to damage the surrounding healthy tissue. When a tumor is located in an especially sensitive area or has infiltrated a critical part of the brain, the surgeon may not be able to remove all of the tumor, and other subsequent treatment options may be necessary.
In some cases and with some tumors, a minimally invasive removal surgery may be possible, lessening the chance of infection and shortening recovery time.
Radiation therapies involve using high-energy x-rays to target and kill tumor cells directly. The beams of radiation are typically focused on the tumor so that they do not damage healthy cells. In some cases, such as when metastatic cancer has spread to the brain from another part of the body and produced multiple brain tumors, radiation may be directed at the entire brain.
Radiation therapy is often used when the tumor can’t be entirely removed with surgery.
Side effects of radiation therapy may include headaches, memory loss, fatigue, and scalp reactions.
Chemotherapy uses chemicals that intentionally damage the body’s cells with the expectation that healthy cells can more easily recover from the damage than the tumor cells can. Chemotherapy can effectively treat some tumors, but its success rate is not high in treating most brain tumors. One obstacle is the body’s blood-brain barrier, a border of cells that protects the brain by blocking the transmission of many substances from the circulatory system into the vulnerable brain tissue. The blood-brain barrier may prevent chemotherapy drugs from reaching the tumor.
Some emerging therapies have shown promise in treating certain types of brain tumors.
- Immunotherapies help the body’s immune system to recognize and fight tumor cells.
- Targeted drug therapies use medications to attack vulnerabilities unique to the tumor cells, leaving healthy cells alone.
- Angiogenesis inhibitors work to starve the tumor of blood flow it needs to grow.
- Gene therapies aim to introduce a gene into cancer cells that will inhibit their growth.
Depending on the type and specifics of the tumor, some of these therapies may be used in conjunction with more traditional treatments.
How Does A Brain Tumor Progress?
As a brain tumor grows, it will first affect the body functions controlled by the part of the brain where the tumor is located. This may result in movement difficulties, for example, if the tumor is located in the area of the brain that controls motor function.
If the tumor continues to grow, causing damage or swelling in the whole brain, the initial effects will become more pronounced, and effects on the entire body will begin to emerge.
Later-stage effects can include:
- Difficulty in moving or controlling movements
- Speech difficulties, including difficulties understanding speech
- Memory loss
- Loss of strength
- Impaired judgment
- Extreme changes in personality or mood swings
How Is A Brain Tumor Prevented?
Because there are so many different types of brain tumors, and their causes are so poorly understood, there is no clear way to prevent them from occurring. Even the lifestyle changes that can decrease the risk of many other types of cancer, such as quitting smoking or maintaining a healthy weight, may not reduce the chance of developing a brain tumor.
The only widely accepted preventative measure for brain tumors is the avoidance of high doses of radiation to the head.
Brain Tumor Caregiver Tips
Caring for someone with a brain tumor can be even more challenging than the already high demands of caring for someone with any other type of serious and progressive illness. Along with the physical changes that make other cancers and serious illnesses so physically and emotionally exhausting to deal with, brain tumors also often produce psychological and cognitive changes in the patient that can threaten the caregiver’s well-being, too.
As you care for your loved one through the progressive stages of their illness, keep these tips in mind:
- Learn as much as possible about the potential effects of your loved one’s specific type of brain tumor. This will allow you to understand how the illness is affecting the sufferer’s behavior.
- Get help from your friends and family. Caring for a brain tumor patient is a huge task, and you shouldn’t try to do it alone.
- Take time whenever possible to step away from the patient and the illness and find time for yourself. Acknowledge that it is normal and acceptable to need occasional relief from the burdens of caregiving.
- Find a support group. It can be immensely helpful to learn that you are not alone and that other people understand what you are going through.
Brain Tumor Caregiver Tips
Researchers are currently working on projects that could increase our understanding of brain tumors and improve brain tumor patients’ prognosis. Research is ongoing in areas ranging from risk factor identification to early diagnosis and more effective treatment.
Some currently active areas of research include:
- Gene research. Scientists are working to find the genes responsible for the development of certain tumors. This research could help us understand who is at risk for developing certain tumors and find ways to prevent tumor development.
- Blood-brain barrier research. Scientists are also trying to find ways to temporarily and safely disrupt the blood-brain barrier so that drug treatments can more effectively be delivered to the site of tumors.
- Targeted drugs and viral therapies. Research is ongoing into drugs and viral agents that can precisely and effectively attack cancer cells without damaging healthy cells.
- Imaging technologies. New imaging technologies are being developed that may detect tumors at earlier stages or monitor the effects of treatment on existing tumors more closely.
Brain Tumor Research
Title: Local Control, Quality of Life and Toxicities in Adults With Benign or Indolent Brain Tumors Undergoing Proton Radiation Therapy
Principal investigator: Helen A. Shih, MD
Massachusetts General Hospital
The main purpose of this study is to see how well the tumor is responding to the Proton Radiation up to 5 years after the participant receives it. The investigators are also looking for how this type of radiation affects the quality of life as well as any side effects the participant may have after the radiation is administered.
The FDA (the U.S. Food and Drug Administration) has not approved Proton Radiation for this specific disease, but it has been approved for other uses.
Title: Cognitive Biomarkers in Pediatric Brain Tumor Patients
Principal investigator: Josh Rubin, MD, PhD
Washington University School of Medicine
St. Louis, MO
The investigators will focus on three cohorts of brain tumor patients aged 4-18 years to answer two critical questions: 1) Can the investigators acquire high-quality data relevant to cognitive function during the peri-diagnostic period and, 2) can the investigators develop predictive models for cognitive outcomes using serial examination of functional imaging and cognitive function. Any patient with a newly diagnosed brain tumor aged 4-18 will be eligible for enrollment in cohort 1. Only patients with previously diagnosed tumors of the posterior fossa will be eligible for cohort 2. For cohort 3, eligible patients will include patients with a clinical diagnosis of posterior fossa syndrome with physical impairments that prohibit completion of the NIH Toolbox Cognitive Battery. The investigators have decided to expand the eligible tumor types to better capture the most significant deficit variability that can be caused by tumors outside the posterior fossa. Thus, this focus will provide a platform to analyze the impact of different tumor types and different standard treatments on cognitive dysfunction.
Title: CSF Biomarkers for Brain Tumors
Principal investigator: Terry C. Burns, MD, PhD
Most brain tumors remain incurable. The gold-standard outcome measure for neuro-oncology clinical trials is overall survival. More detailed information is needed to guide individualized therapies and expedite progress. Cerebrospinal Fluid (CSF) is an underutilized source of potential biomarkers for brain tumors. This study aims to generate a repository of CSF samples with at least 2 timepoints per patient. Such samples are of particular importance to identify quantitative biomarkers of disease burden and response to therapy.