Your doctor will recommend treatment depending on the type and location of the tumor. Before treatment begins, it's important to reduce the pressure within the skull. Steroid medications are often used to do this.
The main treatments for brain tumor are surgery, radiation, and chemotherapy alone or in combination. New surgical and radiation techniques that lessen the risk and discomfort associated with traditional brain surgery may be available. These procedures might allow patients with primary brain tumors to avoid or postpone traditional surgery and often produce similar results. Treatment for children may be different from treatment for adults. Some of the treatments that are tolerated by an adult's brain can prevent normal development of a child's brain.
The chance of success depends on the type of brain tumor and the patient's general health.
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The majority of brain tumors are treated with surgery. First, a part of the skull is removed to get to the brain in a craniotomy. (After the surgeon removes the tumor, the bone is usually put back, or the opening in the skull is covered with a piece of metal or fabric.) The challenge is to remove as much of the tumor as possible without injuring normal brain tissue that controls functions such as speaking, walking, and thinking. A tumor can recur if any tumor cells are left.
In the past, surgeons looked for subtle differences in the appearance of normal tissue and the tumor to determine how much tissue to remove. This frequently resulted in complications. In the early 1990s, computerized devices called surgical navigation systems were developed that enable the surgeon to study an image of the patient's brain on a computer in the operating room, match it to the patient's head, and more accurately determine the location and size of the tumor. These tools have greatly reduced the risk of complications from surgery and have allowed surgeons to remove some tumors that were once considered inoperable.
One limitation of these systems is that they use CT and MRI scans obtained prior to surgery to guide the surgeon. However, these scans can't account for movements of the brain that occur during surgery. In certain cases, some type of imaging is used during surgery, such as ultrasound, CT scan, or even MRI, to provide surgeons the most accurate information.
Sometimes surgery isn't possible. If the tumor is in the brain stem, for example, a surgeon may not be able to remove it without harming healthy tissue. Also, in some cases, surgery may not be necessary as the tumor is likely to respond to other treatments. In these cases, the patient may receive chemotherapy or radiation.
Chemotherapy uses drugs to kill or stop the growth of cancer cells. It can be used alone or in addition to surgery or radiation therapy. Traditional " cytotoxic " chemotherapy is a systemic treatment, taken by pill or by a needle in the vein, muscle, or artery that travels through the bloodstream killing cancer cells throughout the body. It works by causing cell damage that normal tissue can repair better than tumor tissue can. The drugs are often given in cycles to allow for recovery after each treatment.
Chemotherapy has had mixed success in the management of brain tumors. However, it's clearly effective against certain pediatric tumors and some oligodendrogliomas, which are typically low-grade tumors that arise in the cells that produce myelin, a fatty substance that coats brain cell nerve fibers. It's been proved that chemotherapy improves survival rates in about 20 percent of patients with the most malignant of primary brain tumors, and tests predicting sensitivity to these drugs are beginning to emerge for certain tumors. In many cases, chemotherapy is now part of the standard of care in the treatment of some malignant adult brain tumors.
One possible explanation for chemotherapy's ineffectiveness in some cases is that the drugs used might be unable to pass from the bloodstream into the brain through the blood-brain barrier that keeps damaging substances—and potentially beneficial medications—from traveling through the bloodstream to the brain. Some investigators have tried to improve the effect of chemotherapy by disrupting this barrier, and results have been encouraging in a certain type of tumor called primary central nervous system lymphoma.
Recently, new ways of delivering chemotherapy directly into tumor or brain tissue have allowed patients to receive chemotherapy or new types of medications without the systemic side effects. Chemotherapy wafers applied in the tumor at surgery slowly secrete chemotherapy into the tumor. Investigational infusion (slow, continuous injection) of chemotherapy called " convection enhanced delivery " is also being used in some cases.
Drugs that are aimed not at killing the cells but rather at changing growth or altering other cell functions are also being used. These growth modifiers, often called small molecule drugs or targeted therapies, have been shown to stop or shrink some primary tumors that resist other treatments. New drugs in this class are actively under development.
Radiation therapy treats disease using high-energy rays or radioactive substances. The radiation is directed at the tumor to kill or damage cancer cells. Radiation can be used instead of surgery in some cases to shrink tumors, or after surgery to try to kill any cancer cells that may remain. Because radiation therapy to the brain can affect growth and brain development in young children, clinical trials are studying ways of using chemotherapy to delay or reduce the need for radiation therapy.
Fractionated radiation therapy uses X-rays produced by a machine called a linear accelerator or a cobalt machine to kill cancer cells from the outside and shrink tumors (external-beam radiation therapy), usually delivered daily over weeks. Radiation therapy may also place materials that produce radiation (radioisotopes) into the tumor to kill cancer cells from the inside (internal radiation therapy or brachytherapy). Hyperfractionated radiation therapy is a way of giving radiation therapy in smaller-than-usual doses two or three times a day instead of once a day. Hypofractionated radiotherapy uses larger doses in fewer treatments than conventionally used for that tumor. The way the radiation therapy is given depends on the type and stage of the tumor being treated.
Side effects of radiation therapy, which result from damage to normal tissue as well as cancerous cells, can include nausea, headaches, fatigue, vision changes, hair loss, and eventual memory loss and cognitive impairment.
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The aim of radiation treatments when applied to brain tumors is to selectively kill the tumor while leaving normal tissue (often mixed with the tumor cells) unharmed. Traditionally, multiple treatments of low-dose radiation are applied to the tissue, usually over a period of two to seven weeks. Each treatment damages both healthy and cancerous tissue. By the time the next treatment is given, the theory is that most of the normal cells have repaired the damage while the tumor cells have not. This treatment is repeated 10 to 30 times, depending on the type of tumor. Ideally, the vast majority of the tumor will be killed, and the vast majority of the normal tissue will survive. Researchers think that the process that kills the tumor cells is one in which the cell recognizes irreparable damage and self-destructs. Unfortunately, this mechanism is not intact in all tumor cells, and the remaining tumor cells usually regrow, especially if the tumor was large.
Depending on the patient's tumor location and size, radiation may either be focused on one area or directed at the entire brain (whole brain radiation therapy). Drugs that may enhance the effect of radiotherapy (radiation enhancers) are currently being investigated for certain types of tumors.
For some patients, high dose, strategically directed radiation known as stereotactic radiosurgery delivered over one to five days may be a better treatment option. A single radiosurgery treatment can only be used to treat tumors of a limited size since larger tumors require less focused radiation. Radiosurgery works well for many benign and malignant tumors and can be used instead of conventional radiation or surgery or in combination with these treatments.
Stereotactic radiosurgery uses precisely targeted beams of radiation that are targeted directly at the tumor while causing little damage to healthy surrounding tissue. The procedure typically produces results dramatic enough to be deemed "surgical." During stereotactic radiosurgery, the tumor is pinpointed using MRI or CT. The patient is fitted with a head frame or other immobilization device that is positioned in a special machine so the radiation can be directed at the tumor. In one common type of radiosurgery, the patient lies on a bed that slides into a machine, which delivers the radiation from radioactive cobalt through 201 ports inside the helmet. The beams intersect at the tumor target. Other types use linear accelerators with devices to match the shape of the delivered radiation to the tumor. When similar techniques are used with lower doses over more sessions, this is called stereotactic radiotherapy.
Stereotactic radiosurgery is an alternative to conventional surgery when the results are equal or superior to surgery, the risks associated with surgery are too high, or the patient is not a good candidate because of age, health factors, or an inability to tolerate general anesthesia. It is sometimes used in combination with conventional surgery and radiation therapy in order to maximize response while minimizing risk.
Not all patients are cured with standard therapy, and some standard treatments may have more side effects than are desired. As a result, some people with brain tumors participate in clinical trials. Clinical trials are research programs conducted with patients to evaluate new medical treatments, drugs, or devices. They are ongoing in most parts of the country for most types of adult or pediatric brain tumor. Some of the therapies being studied include:
Immunotherapy: This uses the immune system, the body's natural defense against infection and disease, to fight cancer. Immunotherapy uses substances made by the body or made in a laboratory to boost, or restore, the body's natural defenses against disease. In theory, the body's immune system should recognize tumor cells as abnormal and then attack and destroy them. This immune surveillance probably occurs daily and destroys many early tumor cells. A tumor cell might develop, however, that can fool the immune system by making substances that block the signals that tell the immune system to seek and destroy the abnormal cells. Or the body's immune system might be weakened by HIV infection, drugs, or alcoholism and allow tumor cells to escape control.
Animal studies have shown that a healthy immune system that is being fooled by the tumor can be taught to recognize the tumor and resume its control duties. Researchers have been working on a variety of brain tumor vaccines that teach the patient's immune system to attack a previously cloaked primary tumor.
Immunotherapy represents a promising new class of treatments that, in theory, could confer lifelong immunity to a variety of tumors affecting the brain. Other promising means of using the immune system to treat tumors include tagging potent toxins to antibodies (immunotoxins) that selectively seek out the tumor cell, so that only the tumor cells receive the poison, delivered through slow, continuous infusion over several days. This process is called convection-enhanced delivery.
Gene therapy: The goal of gene therapy is to repair or replace the defective genes that may be causing a tumor to grow. Perhaps the most appealing means of curing brain tumors is to correct the underlying defects in the genes that direct tumor control. Genes that promote growth could be turned off, those that suppress growth could be turned on, defective monitoring mechanisms could be turned on, genes that produce a beacon for the immune system could be delivered, and so on. Gene therapy has been used successfully in mice to rid them of primary and secondary tumors. The principal problem with gene therapy as the primary treatment of brain tumors is that, in theory, every tumor cell must be treated with gene therapy. If even one cell escapes, it could regrow into a large tumor.
While it is possible to inject enough reparative genes into a tumor in a mouse to eradicate the tumor, it is quite a different thing to inject enough gene therapy into a human brain tumor, which is likely to be much larger. To date gene therapy has been shown to kill human tumor cells; unfortunately, current delivery mechanisms are inefficient and unable to deliver enough to cure the whole tumor. Nonetheless, gene therapy might well become an important future treatment of human brain tumors, alone or in combination with the above therapies.
Many tumors produce substances that promote the growth of new blood vessels to help provide oxygen and nutrients for their nearly insatiable needs. Eventually, these tumor cells become dependent on these new vessels. A promising new technique is to use substances (antiangiogenesis factors) that inhibit these blood vessels, thereby starving the tumor cells. These factors can obliterate certain malignant tumors in mice and early human trials have shown response in some cases, although usually not prolonged. Furthermore, there are situations in which production of new blood vessels is important for health. The role of antiangiogenesis factors in humans is promising, particularly in combination with other drugs, but remains to be defined.
Last reviewed on 10/9/09
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