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Brain Tumors, Malignant

With an incidence of 4.5 per 100,000, malignant brain tumors (gliomas, meningiomas, and schwannomas) are common (slightly more so in men than in women).

Tumors may occur at any age. In adults, incidence is generally highest between ages 40 and 60. The most common tumor types in adults are gliomas and meningiomas; these tumors are usually supratentorial (above the covering of the cerebellum).

In children, incidence is generally highest before age I and then again between ages 2 and 12. The most common tumors in children are astrocytomas, medulloblastomas, ependymomas, and brain stem gliomas. In children, brain tumors are one of the most common causes of death from cancer

Causes

The exact cause of pediatric brain tumors is unknown. Some tumors have been linked to hereditary syndromes, such as neurofibromatosis type I and type II, tuberous sclerosis, and von Hippel-Landau disease. While studies have shown no clear environmental link, radiation therapy can cause tumors to develop. Patients with immunodeficiency diseases like Wiskott-Aldrich syndrome or AIDS are also more likely to develop these types of lymphomas.

Signs and symptoms

Brain tumors cause central nervous system changes by invading and destroying tissues and by secondary effect mainly compression of the brain, cranial nerves, and cerebral vessels; cerebral edema; and increased intracranial pressure (ICP). Generally, clinical features result from increased ICP; these features vary with the type of tumor, its location,and the degree of invasion. The onset of symptoms is usually insidious, and brain tumors are commonly misdiagnosed.

Symptoms of brain tumors are related to:

• Size and location of the tumor
• Pressure on surrounding structures of the brain
• Increase in pressure within the brain
• Child's age

Diagnosis

In many cases, a definitive diagnosis follows a tissue biopsy performed by stereo tactic surgery. In this procedure, a head ring is affixed to the skull, and an excisional device is guided to the lesion by a computed tomography (CT) scan or magnetic resonance imaging (MRI).

Other diagnostic tools include a patient history, a neurologic assessment, skull X-rays, a brain scan, a CT scan, MRI, and cerebral angiography. Lumbar puncture shows increased pressure and protein levels, decreased glucose levels and, occasionally, tumor cells in cerebrospinal fluid (CSF).

Treatment

Remedial approaches include removing a resectable tumor; reducing a non­resectable tumor; relieving cerebral edema, increased ICP, and other symptoms; and preventing further neurologic damage.

The mode of therapy depends on the tumor's histologic type, radio sensitivity, and location and may include surgery, radiation, chemotherapy, or decompression of increased ICP with diuretics, corticosteroids or, possibly, ventriculoatrial or ventriculoperitoneal shunting of CSF.

• Gliomas. Treatment usually requires resection by craniotomy, followed by radiation therapy and chemotherapy. The combination of nitrosoureas (car­mustine [BCNU], lomustine [CCNU, or procarbazine) and postoperative radiation is more effective than radiation alone.
• Astrocytomas. Surgical resection of low-grade cystic cerebellar astrocytomas brings long-term survival. Treatment of other astrocytomas includes repeated surgery, radiation therapy, and shunting of fluid from obstructed CSF pathways. Some astrocytomas are highly radio­sensitive, but others are radioresistant.
• Oligodendrogliomas and ependymomas. Treatment includes resection and radiation therapy.
• Medulloblastomas. Treatment involves resection and, possibly, intrathecal infusion of methotrexate or another antineoplastic drug.
• Meningiomas. Treatment requires resection, including dura mater and bone (opemtive mortality may reach 10% be­cause of large tumor size).
• Schwannomas. Microsurgical technique allows complete resection of the tumor and preservation of facial nerves. Although schwannomas are moderately radioresistant, postoperative radiation therapy is necessary.

Chemotherapy for malignant brain tumors includes the nitrosoureas that help break down the blood-brain barrier and allow other chemotherapeutic drugs to go through as well. Intrathecal and intraarterial administration of drugs maximizes drug actions.

Palliative measures for gliomas, astrocytomas, oligodendrogliomas, and ependymomas include dexamethasone for cerebral edema and antacids and histamine-receptor antagonists for stress ulcers. These tumors and schwannomas may also require anticonvulsants.

Surgery, radiation and chemotherapy are used to treat a tumor. But your spiritual well-being may benefit from complementary therapies such as meditation, yoga, imagery, prayer, massage, relaxation and humor. You can explore these therapies on your own or ask your medical care team for suggestions. However, don't take any herbal products or dietary supplements without consulting your physician.

Experimental therapies that may be used to treat brain cancer include the following:

• stereotactic radiosurgery - a new technique that focuses high doses of radiation at the tumor site, while sparing the surrounding normal tissue, with the use of photon beams from a linear accelerator or cobalt x-rays.
• gene therapy - a special gene is added to a virus that is injected into the brain tumor. An antivirus drug is then given which kills the cancer cells that have been infected with the altered virus.