There are over 140 different types of brain tumors that can form in the brain. Brain tumors can be classified as primary or metastatic, depending on where they arise in the body. Primary brain tumors originate in the brain and rarely spread outside of it. Metastatic tumors begin in another part of the body and spread to the brain through blood or lymphatic tissue. Some cancer types are more prone to spreading to the brain. These types include breast cancer, kidney cancer, melanoma, and lung cancer.
Brain Tumor Causes
We don't know exactly what causes brain tumors, but studies do suggest that there may be many factors that play a role in their development. Risk factors for brain tumors include:
- exposure to radiation
- family history of certain genetic disorders like neurofibromatosis, tuberous sclerosis, Von Hippel-Lindau disease, and Li-Fraumeni syndrome
- having a compromised immune system (more so associated with CNS lymphomas and people infected with AIDS)
Symptoms of Brain Tumors
Brain tumor symptoms vary based on the location of the tumor within the brain and the size of the tumor. Severity of symptoms does not indicate how large a tumor is - small tumors can cause severe symptoms. Headaches are a common symptom of brain tumors, but are usually accompanied by another symptom. Brain tumor associated headaches often have characteristics that set them apart from headaches that re related to less serious conditions. Contrary to popular belief, headaches are not usually the initial symptom a person experiences - it is actually a seizure or muscle weakness that is most often the first symptom a brain tumor presents.
Other brain tumor symptoms include:
- nausea and/or vomiting
- visual and hearing disturbances
- problems with memory
- slower thought process
- weakness on one side of the body or abnormal gait
- fatigue or increased sleep
- personality changes
Diagnosing Brain Cancer
If a doctor suspects a brain tumor, one of the first steps in getting an accurate diagnosis is through magnetic resonance imaging (MRI). This imaging test gives physicians an extraordinary view of the brain and this is often the only test needed to identify the possible presence of a brain tumor. In some limited cases, a CT scan may be used. PET scans, which help doctors see the activity of the brain, may help diagnose primary brain cancer but their use is less certain with a metastatic disease.
Ultimately, it is a brain biopsy that confirms the malignancy and type of brain tumor present. If tumors are present as shown on an MRI and a person suffers from a type of cancer that is known to metastasize, then a biopsy may not be necessary. However, with types of cancer that don't often spread to the brain, a biopsy is a vital diagnostic tool. Primary brain tumors most always require a biopsy.
Brain biopsies can be done during times of surgical exploration or open surgery. The sample tissue can be examined in the operating room, allowing the surgeon to make a decision about whether to proceed with surgical treatment or not. More extensive evaluation of the tumor specimen will also be done by a pathologist. It may take several days to receive results.
In some cases, a closed biopsy, also called a stereotactic biopsy, is performed when the tumor is located in a region of the brain that is difficult to reach. It is the least invasive type of biopsy, but does carry risks.
Treatment of Brain Tumors
Brain tumors are treated by an experienced group of medical professionals that may be called your "treatment team." The team is composed of a neurosurgeon, medical oncologist or neuro-oncologist, radiation oncologist, and a pathologist. Many other supporting team members also provide care, such as oncology nurses.
The tumor type, location, and grade will determine the treatment plan. Curative treatment is possible with some tumors, while slowing the growth or simply relieving severe symptoms may be the goal of treatment for others. Unfortunately, there may be no recommended course of treatment for some brain tumors.
Surgical approaches in brain tumor treatment include tumor resection (complete removal) or debulking (removing as much as possible). In some cases, surgery may be the only treatment method that is required, but others may need other treatment methods, like radiation therapy. Surgery followed by radiation therapy is common with many tumors, however. There are several types of radiation therapy used to treat brain tumors. Again, tumor type, grade, and location are key factors in deciding which type of therapy is best.
Radiation therapy does not come without risks, however. It can damage parts of the brain, leading to cognitive decline, like memory loss and trouble concentrating. Swelling can be a side effect, but can be controlled with corticosteroids. Radiation necrosis can also be a side effect of radiation. In simple terms, it is the formation of irradiated brain tissue that has died and developed into a mass. Surgery may be needed to to remove the dead tissue.
Chemotherapy may be utilized in some tumors that are known to respond well to chemotherapy agents, such as CNS lymphoma, gliomas, or medullablastomas. Some higher grade tumors respond well, but not all. Thus, chemotherapy is available to select patients whose tumors are favorable to chemotherapy.