Astrocytoma is one of the more common types of glioma. It is a primary tumor of the brain. It develops from the line of glial cells called astrocytes. Astrocytes are not neurons (the nerve cells that generate electrical impulses in the brain). Instead, their role is to maintain the neurons, repair tissue in the central nervous system and form a barrier between blood and brain.
Astrocytomas arise from genetic mutations which impair the regulation of cell activities such as metabolism, growth, remodeling, replication and tumor suppression. Astrocytomas can occur at any age and are slightly more common in males. There are a variety of named subtypes, such as pilomyxoid astrocytoma, pilocytic astrocytoma and pleomorphic xanthoastrocytoma. Astrocytomas fall into two categories: low-grade and high-grade (also called anaplastic astrocytoma or brain cancer).
- Grade I astrocytomas maintain a relatively high level of cell differentiation (specialized structure and function). They are slow-growing and less aggressive. Pilocytic astrocytoma typically occurs in children and young adults. It can appear “encapsulated” and may be cured by surgery.
- Grade II (diffuse) astrocytomas are also slower growing, but their tumor cells creep or infiltrate into the surrounding brain. Over the course of many years, more genetic mutations can accumulate. The tumor cells become less differentiated (anaplastic) and transform into a high-grade tumor. This process is termed malignant transformation.
- Grade III astrocytomas are also referred to as anaplastic or high-grade astrocytomas. These tumors are considered malignant or cancerous. They behave more aggressively. Certain molecular features, such as the mutation status of the IDH1 gene, can be tied to the outlook (prognosis).
- Grade IV astrocytomas are also referred to as glioblastoma. It is the most poorly differentiated glial tumor and, in general, carries the worst prognosis for progression-free and overall survival. Molecular markers are playing an increasingly important role in identifying the tumor’s behavior and its potential response to treatment.
Signs and Symptoms
Symptoms generally depend on the size and location of the tumor. Symptoms can be produced by altered brain function within the area of the tumor or by the tumor exerting pressure on normal areas. If edema (swelling) develops around an astrocytoma, symptoms may increase or worsen.
Some of the more common symptoms associated with an astrocytoma may include:
- New or worsening headache
- Nausea and vomiting
- Difficulty thinking
- Difficulty speaking or reading
- Blurry vision
- Weakness in an arm and/or leg
- Difficulty with balance or walking
- Confusion, irritability or personality change
- Drowsiness or lethargy
The exact cause of an astrocytoma is not fully understood. Abnormalities (mutations) in genes that control the cell cycle (cells growth, division and death) of astrocytes lead to their unregulated cell growth.
The presence of symptoms often leads to a physician visit. Many other conditions can produce similar symptoms. Diagnosis begins with the medical history and physical examination. Other tests are used to establish the diagnosis and help guide treatment. These may include computerized tomography ( CT ) scan of the brain, magnetic resonance imaging ( MRI ) scan, functional MRI ( fMRI ), MRI perfusion scan and/or a positron emission tomography ( PET ) scan. CT is often the first test obtained. Use of a stereotactic biopsy may be indicated in certain situations.
A customized treatment plan is put together for you based on:
- The type, location and size of your tumor
- Your age, general health and tolerance for a particular treatment
- Your preferences
Depending on the grade, size, location and molecular findings, treatment may include one or a combination of the following options:
- Craniotomy Direct surgery on the brain is called a craniotomy, which may be open or minimally invasive. When possible, craniotomy to remove the tumor is the first step. It establishes the definite diagnosis and provides initial treatment. This surgery is best performed by specialized neurosurgeons experienced in operating on brain tumors. Your neurosurgeon will use magnification, often with a high-powered operative microscope, and a computer-guided imaging system to navigate precisely around the tumor during the craniotomy. Fluorescence- guided resection incorporates a special dye to help define the tumor while using the operative microscope. Unfortunately, individual tumor cells may already have crept beyond the apparent border of the tumor into normal brain which means that additional treatments may be needed. Generally you will stay in the hospital for a few days after surgery, with the length of stay determined by the extent of surgery and your medical condition.
- Other treatments A variety of treatments may be employed to treat the tumor itself. These include chemotherapy, immunotherapy and radiation therapy and will depend upon your particular tumor.
- Steroids These medicines may improve or even provide temporary relief of symptoms from your astrocytoma by reducing the edema (swelling) around the tumor. The most commonly used steroid in neurosurgery is dexamethasone (Decadron®).
- Anti-seizure medicine This type of medicine is used to prevent further seizures. Sometimes, anti-seizure medication may be used for a short period around the time of surgery. A tumor can alter the normal electrical activity in the brain and produce a seizure. This is a surge of synchronized electrical activity that can produce altered awareness or consciousness, repetitive shaking or stiffness, or loss of bowel/bladder function.
- Therapies A brain tumor and its subsequent treatments may affect your motor skills, speech, swallowing or cognitive abilities depending on its size and location. Physical, occupational and speech therapies may be used to help regain or compensate for any diminished abilities. These rehabilitative therapies may be performed in an inpatient or outpatient setting.
Follow-up care typically includes regular monitoring of your clinical condition as well as routine surveillance of your imaging studies (usually MRI or CT scans). You may be seen in a coordinated fashion by the specialists who may have been treating you (neurosurgeon, radiation oncologist and medical oncologist).