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Brain Cancer Treatment
By peace | December 10, 2006
The brain, like any other tissue in the body, is made up of individual cells which are much smaller than a pinpoint, and require a microscope to see them. These cells are the smallest units which compose the brain, and there are several different types. A brain cancer can arise from any of the cells which make up the brain. Basically, the brain’s thinking cells (called “neurons”) are meant to divide rapidly before birth, and up until about 7 years old. At this time the brain is fully grown, and contains all the “neurons “that it ever will. Further development is by the existing cells making increasingly elaborate connections with each other, to communicate with one another.
Once the brain cells stop dividing in childhood, they are never meant to divide again. If the brain is injured, such as by trauma or a stroke, specific cells within the brain (the “glial cells” ) divide to form scar tissue, but the brain’s thinking cells (the neurons) don’t reproduce (although damaged ones may be repaired). You can see that the division of brain cells is under strict regulation and control. When this control is lost in a single cell, then it starts dividing in an uncontrolled manner. Brain cancer starts in just one cell. As the cell makes more and more copies of itself, it grows to form a tumor (which means a swelling). A benign tumor stays where it starts, although it can grow very large and press on crucial areas. In contrast, a malignant tumor has a capacity to spread, and is then called “brain cancer”. “Primary” brain cancer starts within the brain. In contrast, “secondary” brain cancer starts in some other organ (like lung or breast) and then spreads to the brain. This is called “brain metastasis”.
Diagnosis Of Brain Cancer
A tumor simply means a swelling, and isn’t necessarily cancer. A patient will come to the doctor with symptoms suspicious for a brain tumor, and the physician will perform a neurological examination to check the nerves or the brain which control the eyes and face, check for equal strength and sensation on both sides of the body, coordination and balance, and memory and judgment. He will look into the eyes for signs of increased pressure in the skull, such as swelling of the optic disks.
The first step in diagnosing brain cancer involves evaluating symptoms and taking a medical history. If there is any indication that there may be a brain tumor, various tests are done to confirm the diagnosis, including a complete neurological examination, imaging tests, and biopsy.
Treatment Of Brain Cancer
Treatment for brain cancer depends on the age of the patient, the stage of the disease, the type and location of the tumor, and whether the cancer is a primary tumor or brain metastases. The treatment plan is developed by the oncology team and the patient.
Treatment involves any combination of surgery, radiation, and chemotherapy. Some tumors require several different surgical procedures, and some can be treated with radiation alone.
1. Surgery
Surgery is the treatment of choice for accessible primary brain tumors, when the patient is in good health. The goal of surgery is to remove as much of the tumor as possible without damaging nearby normal brain tissue. The prognosis improves when more than 90% of a tumor can be removed.
Removal is often complicated by the nature of the tumor (e.g., invasive, highly vascularized) and by its location. Partial removal (debulking) of the tumor can improve quality of life by alleviating symptoms and sometimes improve the effectiveness of radiation therapy or chemotherapy.
Before surgery, some important tests are performed. Patients over the age of 40 usually undergo an electrocardiogram (ECG or EKG) and a chest x-ray. Other tests are used to detect the presence of uncontrolled hypertension, diabetes, active coronary ischemia, or the presence of circulating anticoagulant (substance that inhibits normal blood clotting) in the blood. If any of these conditions are present, it may not be advisable to undergo craniotomy.
2. Craniotomy
Craniotomy is the treatment of choice and the goal is to remove as much of the tumor as possible. The procedure is performed under general anesthesia and involves opening the skull (cranium).
The neurosurgeon makes an incision into the scalp and several holes (called burr holes) are made in the skull. A bone saw is used to join the holes together to create a flap of bone.
The bone flap is then removed to expose the brain and remove as much of the tumor as possible. After the tumor has been partially or completely resected, the bone flap is replaced and secured using fine wire. Recovery from the procedure may take as long as 8 weeks.
Complications of craniotomy include bleeding (hemorrhage), swelling (edema), increased intracranial pressure (IICP), infection, and brain tissue damage.
In laser microsurgery, MRI is used to pinpoint the location of the tumor and a laser is used to destroy the tumor. This procedure may be used after craniotomy to remove remaining tumor tissue.
Brain-mapping is performed under local anesthesia and sedation. Electrodes stimulate nerves in the brain, measure responses, and allow communication with the patient. The surgeon removes as much of the tumor as possible without damaging vital areas of the brain, such as those that control motor function and speech.
In some cases, a chemotherapeutic agent called BCNU is used following surgery. In this treatment, the neurosurgeon places a wafer soaked with BCNU (Gliadel®, BiCNU®) into the surgical cavity after the tumor has been removed. By applying it directly to the diseased area of the brain, side effects are limited and the drug has a more beneficial effect.
Postoperative care includes drug therapy with corticosteroids, histamine inhibitors (block stomach acid), and antiepileptics. Corticosteroids (dexamethasone and Decadron®) help reduce swelling and can relieve various postoperative neurological effects.
An MRI scan, with and without contrast, is often obtained to determine the extent of residual disease following surgery. Sometimes, a plan for rehabilitation is needed.
3. Radiation Therapy
Radiation is used when the entire primary tumor cannot be surgically removed. Most malignant brain tumors are treated with external-beam radiation even if the entire primary tumor is surgically removed, because hidden tumor cells often remain in brain tissue.
The survival rate for patients with malignant tumors (e.g., anaplastic astrocytoma, glioblastoma multiforme) more than doubles with radiation therapy, and it can prolong life for patients with low-grade gliomas as well.
Radiation therapists use several different approaches to treat primary brain tumors, but external-beam radiation is the most common. Local radiation therapy techniques, including external focal, brachytherapy, and stereotactic radiosurgery, may be administered to selected patients.
There are various other radiation techniques, some of which are being used on an experimental basis. An assortment of technologies, as well as the use of medications and other compounds, can make tumor cells more sensitive to radiation.
External-beam radiation External-beam radiation, the traditional form of radiation therapy, delivers radiation from outside the body. Therapy usually begins a couple of weeks after surgery and is typically repeated at regular intervals for several weeks.
Hyperfractionation is a modified form of external-beam radiation that involves applying less intense but more frequent doses of radiation. Some benign tumors are treated with external-beam radiation to prevent recurrence, even if the entire primary tumor has been surgically removed. They also may be treated with radiation at the time of recurrence.
Stereotactic radiosurgery Stereotactic radiosurgery delivers radiation to the tumor in a single dose and does not involve surgery, as the term may imply. In this procedure, a head frame supporting a CT or MRI scanner may be attached to the skull. With the aid of computer imaging, the radiologist is able to pinpoint the exact location of the tumor and aim the beam of radiation directly at it.
Newer stereotactic techniques do not involve the use of the head frame. Often the radiation is delivered from several different directions, hitting the tumor at various angles.
The advantage of using localized radiation is that the surrounding, healthy tissue is left undestroyed. It often is used in addition to external-beam radiation, especially in cases of malignant gliomas and mestastases that are in deep or sensitive areas of the brain.
Some tumors, however, cannot be treated with the intense local radiation of radiosurgery. For example, tumors near the optic nerves are better treated with several small doses because the optic nerves are especially sensitive to radiation. Stereotactic radiotherapy involves applying many small doses of radiation, using the same imaging techniques used in stereotactic radiosurgery.
Brachytherapy involves implanting capsules containing radioactive substances into the tumor to deliver localized radiation. It is frequently applied to treat recurrent disease in an area previously treated by external-beam radiation.
Advantages of this type of radiation therapy include sparing vital structures close to the tumor and a shorter length of treatment (i.e., hours to days instead of weeks).
Radiation follow-up
Because loss of pituitary function can be a long-term side effect of radiation therapy, an endocrine evaluation is an important part of follow-up care for patients who have received radiation. Neuropsychological testing may also be done to evaluate whether a patient has incurred diminished intellectual activity resulting from brain tumor radiation.
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